【正确答案】 B

【答案解析】[听力原文]
Tutor: Right everyone ... in today's tutorial for "Science, Scepticism and Popular Myth" Marnie and Geoff are going to do a presentation on ... I believe it is ... "Spontaneous Human Combustion".
Marnie: Yes that's right. Geoff and I felt that this topic provided a good example of differences between popular and scientific explanations for so-called mysteries. So to begin with we thought we'd look very briefly at the history of spontaneous human combustion and then have a look at some of the theories that are out there to explain it.
Geoff: But first we'd better start with a definition of spontaneous human combustion. Spontaneous Human Combustion, or SHC for short, occurs when a person's body erupts into flames as a result of some reaction within the body. That is, the body catches on fire but there is no apparent external heat source. This is purported to have happened in numerous cases throughout history, which I think Marnie is going to tell you about.
Marnie: Yes, thanks Geoff. The first recorded account of SHC is attributed to a Danish medical scientist named Thomas Bartholin, who in 1663 claimed he had seen a Parisian woman burn up in flames on a bed. The remarkable thing was that the straw mattress she was sleeping on remained untouched by the fire. Then 10 years later a French man Jonas Dupont published a work specifically devoted to cases of spontaneous human combustion. Since then there have been hundreds of reports of SHC and numerous books have been written on the subject. What emerges from all these reports is that SHC deaths follow a pattern. Firstly, nearly all cases occur in the victim's home. Secondly, in the vast majority of cases the victim's body, including the head, is entirely incinerated by flames except for the extremities-feet, hands and whatnot-which remain completely undamaged by the flames. Third, the surrounding furniture and house reveal no traces of the fire apart from a greasy residue which coats the walls and ceiling.
Geoff: So what theories have been put forth to explain this phenomenon? Well one rationalisation that was popular in the nineteenth century was that in SHC incidents the body caught alight because there were large quantities of alcohol present. In fact, this was the explanation that Charles Dickens used in his novel Bleak House, in which one of the characters dies from spontaneous combustion.
Tutor: Well, if alcohol were the cause then surely we'd see a lot more cases of SHC, wouldn't we?
Marnie: Exactly. So that theory is not popular now. More common now in the popular literature on the subject is the idea that methane gas is the culprit. Apparently, methane gas builds up in the internal organs and is then ignited by enzymes, which are proteins in the body that produce chemical reactions. Another claim is that static electricity is responsible for spontaneous combustion. How this works exactly is never really made clear.
Tutor: So these two theories you just mentioned are not supported by hard science?
Marnie: Well no, not really, though their proponents like to make them sound very scientific.
Geoff: Yeah ... one so-called expert has even invented a new particle called a "pyroton". According to this guy, pyrotons are sub-atomic and interact with cells to create mini-explosions and that's what causes spontaneous combustion.
Mamie: Yes. Basically, spontaneous human combustion is not accepted by the scientific community. Sceptics and scientists contend that this phenomenon does not exist because in each case claiming that the body just spontaneously caught on fire by itself is the least likely explanation.
Geoff: The debate comes down to this. Believers in SHC base their belief on the notion that the human body is very difficult to completely incinerate. They point out that in crematoriums tremendous amounts of heat are needed to completely reduce a body to ashes and that this kind of heat does not occur in a house without the rest of the house catching fire. Hence, spontaneous combustion is the only explanation.
Marnie: But scientists have another theory which is known as the "Wick Effect".
Geoff: But to be fair, before we go on to the Wick Effect, I guess we should mention that though spontaneous human combustion has never been scientifically proven, spontaneous combustion has been observed in objects such as oily rags and bundles of hay.