单项选择题 维护个人利益是个人行为的唯一动机。因此，维护个人利益是影响个人行为的主要因素。以下哪项如果为真，最能削弱题干的论证？（）

单项选择题 听力原文： Piglets may be happy wallowing in the mud, but they get a much better start in life if they are nurtured on a warm waterbed. Instead of snuggling up to their mothers for warmth in their cold pigsty and running the risk of being crushed--a common cause of early death--German scientists said waterbeds could be a safer alternative. When Martin Ziron and researchers at the Institute of Animal Breeding and Genetics in Giessen, Germany tested various heating methods on 1,400 piglets during their first weeks of life, waterbeds won hands down. 'Around 99 percent of the piglets preferred warm waterbeds to any of the alternatives, spending well over half the day lounging about on them and only getting up to feed or play,' New Scientist said Wednesday. The scientists compared the number of injures, which usually occur while scrambling for a feeding position, and the weight gain of the piglets which were provided with plastic plates, foam mats waterbeds, straw or concrete. Piglets on the waterbeds had fewer injuries and gained much more weight than the animals kept on concrete. According to the magazine, the waterbeds are made from a tough plastic membrane and can be heated from underneath by an electric mat or from above by infrared lamps.From the passage we know that pigletsA．easily get crushed in the first weeksB．does not like warm waterbeds in the beginningC．generally like snuggling up to their mothers for warmthD．are not happy wallowing in the mud

单项选择题 某商场失窃。员工甲、乙、丙、丁涉嫌被拘审。甲说：“是丙作的案。”乙说：“我和甲、丁三人中至少有一个作案。”丙说：“我没有作案。”丁说：“我们四人都没作案。”如果四人中只有一个说真话，则可推出以下哪项结论？（）