Causality means that one of the events happens as the a result of the occurrence of the other event (i.e. one event causes the other to happen).
Direction of causality means we need to know which event causes the other.
Since the only given in this problem in that the two events A and B have a strong linear correlation, therefore, we ave three possible direction on causality:
1- A causes B to occur
2- B causes A to occur
3- Another event or variable causes both A and B to occur at the same time.
