单选题 Researchers have suspected that large portions encourage people to eat more, but studies have begun to______this suspicion only in the last several years.
A. confirm B. contend C. contrive D. concoct

【正确答案】 A
【答案解析】句意：研究人员对食物份量大会促使人们吃得更多这一猜测有所怀疑，但是直到近几年来，研究才逐渐证实了他们这一怀疑。confirm认可；证实。contend虽有“主张；认为”的含义，但其后应接由that引导的宾语从句。contrive“设计，发明”和 concoct“捏造；图谋”均不符合题意。故选A。