The correct answer is 3
Explanation:
Sentence 3 "The US Department of Agriculture recommends that young people ages 6–17 should engage in 60 minutes of physical activity each day" focuses on the importance that young people exercise daily by explaining the time they should spend in exercising and establishing an age rate.
In this context, sentence 3 is ideal to support the point "recreational sports are valuable because youth need to exercise daily" because it directly explains and proves the importance for young people to exercise every day. Also, it is an appropriate piece of evidence because the US Department of Agriculture is an authority in nutrition, healthy habits, and similar.
The correct answer is that they 'are not valid'. If the experiment is biased, it entails that it is not objective. For a experiment, and its results, to be valid, it had to be carried out objectively and taking into account all factors.
It is possible that the results disprove a hypothesis, but to be certain it is necessary to see which was the original objective of the study, as it might also prove to some extent a hypothesis, which is probably also biased.
He didn't stand and speak up. He could have helped
