This is the question:
Medicinal chemists know their latest compound _____ seriously as a drug lead until it _____ its punch in animal models.
A) wasn't taken / proves
B) won't be taken / has proven
C) weren’t taken / would be proven
D) won't take / proves
E) weren't taken / had proved
The answer is "B" but the second part of the answer doesn't make sense. I think it should be "proves" instead of "has proven". Is that right?