一道填空机经的疑问！！

zjusquanchyUID：3683452

Peoples’ decisions about childbearing depend on innumerable personal considerations and societal factors, yet even knowing this, demographers are often ______: their projections of birth rates frequently turn out to be embarrassingly at odds with reality.
A. sanguine
B. flummoxed C. inconsistent D. overconfident E. heartened
F. confounded

题目如上，网上的答案给的是BF，我觉得AD更佳合理啊

逆流的鱼ywjUID：3712130

这个题题干貌似不难懂， 选的应该是innumerable的反面。前面讲innumerable，然后yet转折。冒号表解释，their projections of birth rates frequently turn out to be embarrassingly at odds with reality就是解释这个词的。我也没选对，看来还是单词不过关

逆流的鱼ywjUID：3712130

sanguine：乐观的，确信的，free from doubt。显然不合理
overconfident在感情上倒是没错，但是不能体现出at odds with reality，并且也不是innumerable的反面