PT 55 S1 Q20

A study of rabbits in the 1940s convinced many biologists that parthenogenesis—reproduction ... ...

A flaw in the reasoning of the argument is that the argument:
(A) takes for granted that something that has not been proven to be true is for that reason shown to be false
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Practice Set: "Flawed Reasoning" Questions, Set 3 - Mix (25Q)