In Certain Athletic Events, Such as Marathons and Swimming, __________

In certain athletic events, such as marathons and swimming, __________.

A) the differences in males and females are disappearing as training becomes more equal
B) women have improved so much that they now regularly outperform the men
C) the greater biological capacity for these activities in men has been well documented
D) sex-based differences are rare enough that men and women could compete together