【正确答案】 B

【答案解析】[听力原文]
   Here in the capital of Chiang Mai, hospital workers face an alarming increase in patients suffering from respiratory illnesses, as the haze sets in.
   It's an annual problem caused by excessive field burning in the region during the dry season. But this year's smoke arrived early.
   Thousands of air masks have been distributed to those most prone to illness. But it is seen mostly as damage control for nurses like Saisuda Sutthirat.
   "We have health pamphlets to hand out to patients who have the throat problems and coughing. We teach them how to wear the mask properly."
   Trans-boundary haze has been a growing problem in Southeast Asia as unregulated development moves ahead in places like Laos and Myanmar, also known as Burma.
   A report released last week by the U.S.-based international non-profit organization Forest Trends says that forest conversion for commercial agriculture is now the main reason behind Myanmar's deforestation, which often entails massive burning.
   Thai officials monitoring hot spots in the region say drastic measures must be taken by all countries to reduce the problem.
   "We have reports that the Thai army working on the border has talked with leaders of the neighboring countries, asking them to help to stop the forest fires and make a boundary fire line. But it's still not enough. They have to decrease the hot spots in their country too because the fire didn't just spread across the border but when they burn the forest, the winds blow the smoke into our country and impact the people."
   Many flights have been cancelled or re-directed but solutions are limited and authorities are now adding rain-making and forest fire runs to alleviate the particles of dust.
   For Air Force Captain Phongthep Viwattanadet, who usually douses the flames, the challenge of cutting through the smog is mounting.
   "The haze has impacted our flight visibility. But we have an aviation standard to guide us when it causes problems to our flight. So far we can deal with the visibility and we will continue our water drops until it gets better."
   For now, it seems like the locals will have to wait for the monsoon season to clear things up. In the long term, however, questions remain about how much damage will be inflicted before a proper groundwork can be implemented for a real solution.
   What causes the annual haze in Chiang Mai?
快速浏览本部分各题的所有选项，根据haze、automobile exhausts、field burning、coal、flowing dust、forest、fire等可大致推断，讲座很可能与环境问题有关，很可能讨论了雾霾和焚烧森林的问题。
   四项均是以定冠词the开头的名词短语；四项均提及与环境有关的词汇(automobile exhausts，field burning，coal，flowing dust)，可知题目很可能考查能源或环境问题。本题考查的内容应该是某个细节，且从各选项中的excessive、unrestrained、overuse和large amounts of可推测考查的是一个较负面的问题。听录音时应注意对细节信息的提取以及对整体内容的把握和理解，将重点放在关于问题的名词中心语上。
   讲座前半部分提到，在清迈的首府，随着雾霾的袭来，医务工作者们面对的呼吸道疾病患者的人数呈现出惊人的增长趋势。而旱季该地区田地的过度焚烧使得雾霾成为一年一度的问题。由此可知B为正确答案。其他三项讲座均未提及，可排除。