A recent study compared data on the overall health and lifespans of

The argument says there is some relationship between Alcohol consumption and health of a person.

Moderate consumption means a better lifestyle than no consumption.

Conclusion: Let's cheers with some alcohol as it will make us healthy.

We need to weaken this. Pre assumption: What if people who are drinking it are really healthy and they may stop drinking it because of their poor health.

A. Consuming alcohol in moderation is defined in different ways by different researchers. Irrelevant.

B. Many people who abstain from consuming alcohol do so because they are not healthy. ok, Had the conclusion be true, they should have taken more pegs.
But they are not doing so. Hence, a weakener.

C. The alcohol content of different types of alcoholic beverages varies widely. Irrelevant.

D. The people who consumed alcoholic beverages moderately did not do so in order to experience health benefits. May be there are not aware. They are doing with their friends.

E. The study was designed so that the effects of other lifestyle related variables, such as diet, did not distort the results.: Irrelevant.