Good inputs from the community members so far. Let me add my two cents.

First of all, we need to understand what a weakener can or cannot attack. A weakener cannot attack the information given i.e. premises. So, if it is given that the study found that both drugs and meditations techniques are equally effective when followed over the long run, we cannot say directly "No. They are not equally effective when followed over the long run". However, what we can do is that we can list a flaw in the methodology of the research in finding the effectiveness of drugs and meditation techniques.

Similarly, if it is given that the study found x% people kept using drugs and y% kept using meditation techniques, we cannot say "No. less than x% used drugs OR less than y% used meditations techniques". However again, what we can do is find a flaw in the methodology used to arrive at the numbers or as this question does - make the numbers irrelevant by suggesting that the initial sample for the study was not representative.

Now, coming back to the weakeners suggested:

1. Meditation takes more than 10 years to show results , but most people who practice meditation are unlikely to continue for so long. - This is not a weakener. The conclusion is comparison between drugs and meditation techniques - who is the best one out there? (Remember, the conclusion is finding out the best between the two; not finding the one that cures. May be none of them cures completely). This option statement only talks about meditation techniques and suggest that they cannot cure. However, what about drugs? Can they cure? More importantly, can drugs cure better than meditation techniques? This statement does not suggest anything in this regard.

2. The people who discontinued their medication treatment did so because they were relieved of their symptoms - Not a weakener. We are given that both drugs and meditation techniques are equally effective. This presents information that goes against the information given.

3. The recommended duration for meditation is 10 years,almost twice as long as that of medications - Not a weakener. Goes against the passage. The passage does not differentiate between the duration of drugs and of meditation techniques.