Answer Explanation

@Julie, As you correctly pointed out, the enzyme theory is mentioned in the context of the late nineteenth-century competition between cytology and biochemistry. The passage tells us that the theory is "newly formulated" (line 31) around that time period. The passage also tells us that molecular biology appeared due to the transformation of biochemistry (mostly since 1950) (lines 43-46). Since it clearly happened after the origins of the enzyme theory of life - 1950 versus late 19th century, we can infer that (A) is correct. Let me know if you have any further questions.