单选题 As researchers on aging noted recently, no treatment on the market today has been proved to slow human aging. ______. Those findings suggest that caloric restriction could delay aging and increase longevity in humans, too.

A、 And scientists found that rats fed a low-calorie diet lived longer on average than free-feeding rats and also had a reduced incidence of conditions that become increasingly common in old age.
B、 But one intervention, consumption of a low-calorie yet nutritionally balanced diet, works incredibly well in a broad range of animals, increasing longevity and prolonging good health.
C、 What"s more, animals eating low-calorie diet survived longer than those eating normally, which means that the maximum life span increased.
D、 In addition, studies with monkeys demonstrated that calorie-restricted monkeys have lower blood pressure and a decreased likelihood of heart disease.

【正确答案】 B

【答案解析】解析：本题首句提到“研究者指出目前市场上没有可以减缓人类老化的治疗方法”，但在末句却提到“这些发现表明控制热量也可以使人类延缓衰老，增加寿命”，可见作者在空白部分对首句研究者的观点进行了转折，而且也提到了有关低热量可以延迟衰老的新发现(findings)，纵观选项只有B项用连词but进行了转折，而且提到了“很多动物使用低热量食物后延长生命”的例子，正好与上下文形成连贯，为正确答案。A，C和D项不仅在逻辑连词的使用上出现了问题，而且也出现了语篇语境外词汇，如“areduced incidence of conditions”，“the maximum life span”和“a decreased likelihood of heart disease”，均无法构成连贯的语篇，需排除。