In a recent survey, one out of six Americans were shown to have vision

Answer option E is the right answer here. The key thing to focus on with any question that asks you strengthen/weaken an argument is the overall conclusion arrived at. The conclusion here is that reducing screen time would cause the vision problems to reduce, since screen time is responsible for the vision deterioration. This has not actually established however (since correlation does not equal causation). Hence, what we're looking to do is to either suggest reverse causation, or provide an alternative explanation.

Option A - This just repeats a premise. Even if there is a correlation, we know nothing about the cause. In fact, even if it DID imply causation it would still be wrong, since that would strengthen the argument. OUT

Option B - This is a bit of a trap answer. However, it merely says that the connection is unclear, not that there is NO causation. The problem with this answer therefore is that it is too vague. OUT

Option C - So what? The scope of the argument only pertains to America. In addition, we do not know about vision problems in the rest of the world, so this doesn't affect the argument in any way. OUT

Option D - While a bit vague, this option actually strengthens the argument since it does suggest that the nature of the screen time causes the problems with vision. OUT

Option E - This option offers an alternative explanation, which is that old age is the cause of the problems. By providing a valid alternative explanation, it weakens the logic of the original argument and therefore answers the question correctly. CORRECT