Final answer:
Turning on hazard lights is a safe action to take when driving in rush hour traffic under heavy rain.
Step-by-step explanation:
When driving in rush hour traffic under heavy rain, it is important to take safe actions to ensure your own safety and the safety of others on the road. The safe action to take in this situation is to turn on hazard lights. Hazard lights will make your car more visible to other drivers, especially in heavy rain, reducing the risk of collisions.