Official Explanation
It is critical to work out here whether the physicists mentioned at the end of the sentence were for or against Einstein’s theory. The sentence suggests that the idea went from “purely experiential” to “theoretically” something. There’s a contrast here, and the contrast is not between right and wrong. It is between something that has been shown by experiment and something that has been understood theoretically. The later scientists are providing support for Einstein. “Undermined” and “sabotaged” are negative, while “condoned” and “pardoned” don’t fit the meaning. Only “bolstered” and “buttressed” correctly express the idea of support.
Answer: A,F