This doesn't strengthen. Remember that the argument states that changes in attitudes toward alcoholism have caused physicians to report more deaths as alcohol-related. Nothing in this argument relates to, or is strengthened by, any information about alcohol use by young people being reported as occurring at earlier ages — a fact that could be true whether alcoholism is viewed as a moral failing or as a disease.

This doesn't strengthen. It doesn't matter whether "some places and times" have viewed susceptibility to any kind of disease as a moral failing. We know that in the context of this argument, alcoholism is already no longer viewed as a moral failing, but as a disease. This answer choice doesn't strengthen the idea that it was this change in attitudes that caused physicians to report more deaths as alcohol-related.

This is correct. It explains why, exactly, the change in attitudes toward alcoholism might cause physicians to be more likely to identify deaths as alcohol-related. This answer choice suggests that viewing alcohol as a disease leads more physicians to be trained to recognize the physical signs of this disease, which in turn supports the idea that they will more accurately identify deaths as alcohol-related, where they wouldn't in the past.

This doesn't strengthen. We're not interested in how physicians generally treat alcoholism. We want to know why viewing alcoholism as a disease would make physicians more likely to identify deaths as alcohol-related, compared to when alcoholism was viewed as a moral failing.

This is irrelevant. It might be used as an ad hominem attack against the health officials' argument. But it doesn't strengthen the logic of the main argument, which is focused on the judgments of physicians, not of health officials.