I did not pick D because the sitmulus stated that the levels of this enzyme "were" too low, making it ambigous as to whether these levels were too low after developing cancer or when they were consuming the yogurt in the previous years. If the enzymes "were" too low, in past tense, then this would establish that the proposed cause did in fact exist before the effect, making D not a strong objection. Although it can be reasonable to infer, in the real world, that these levels were likely taken after developing cancer, at the time of the study, the posibility is not ruled out that they had access to the levels of this enzyme prior to developing cancer, and thereofore were refering to the levels prior to the effect. Also, the stimulus just says that these levels WERE too low, not that that is what the study found, making it a fact in the argument and possibly not related to the study, making it possible that these levels were actually refering to the pre-effect time period, rather to just what was true at the time of the study. Therefore, saying that these levels "were" too low, is just ambigous enough to make A the stronger objection. I do understand the strength of A is high, but it does not contain the level of ambiguity that D does, and the question just asks us to find the stronger one.

@CaseyLiu accurate vs complete… we talked about this earlier 😆