Causal hypotheses can be tested only via which research method?

Experimental with random assignment to condition

Explanation:

Causal hypotheses are theories that state how one thing directly causes another. In order to prove this only an experimental research method with random assignment to conditon must be applied. This is because the randomness of assignment prevents researcher intervention and proves that a specific input causes the correct output everytime.

b) trade is easy because of the direct line between their major ports. bilateral trade reached 89,6 thousand million.