Passage

People who exercise often report better sleep. Therefore, exercising often always improves sleep.

Question

What is the flaw in the reasoning?

Answer

It assumes an observed association proves that exercise causes better sleep in every case.

Solution

1. The passage reports a correlation between exercise and better sleep.
2. It does not rule out other causes, such as lifestyle or health.
3. It also overstates the result by claiming it is always true.