Cause

A factory dumps chemical waste into a river. Within weeks, fish die, people get sick, and drinking water becomes unsafe. The factory’s action directly leads to these outcomes. It is the clear starting point of the chain of harm. What did the factory’s action do? It caused the pollution and illness.

Influence (to affect indirectly, without direct force) contrasts with cause, which means to directly bring about an effect or result. Cause implies a clear, traceable link, while influence suggests shaping or guiding without being the sole origin.