which relationship can best described as causal?

Question

(1)height and intelligence
(2)shoe size and running speed
(3)number of correct answers on a test and test score
(4)number of students in a class and number of students with brown hair

Answer 1

1) Does height cause intelligence?
2) Does a larger shoe cause faster running?
3) Does the number of correct answers cause a higher test score?
4) Does the number of students in a class cause the number with brown hair?

What do you think?