which of the following correlation demonstrate a casual relationship?

1 the distance student live from school and the time it takes each to walk there.

2 the amount of money received for allowance and the number of DVD's purchased.

3 the number of hours spend studying and the grades received on exams.

4 high school students' ages and the number of hours they sleep.

is the answer 3???

3 answers

what is wrong with 1?
so is it 1?
If your question is about CAUSAL relationship, not CASUAL relationship, 1 is the correct answer.

There's very little correlation between the number of hours spent studying and the grades received on exams.