In this food chain energy moves from one living thing to another. What source of energy starts this food chain?

It is usually a plant or something that can make its own food

plants make their own food by photosynthesis plants such as grass are eaten my other animals (e. g. cows)

However, the energy that gives the light photosynthesis is the sun.

all things that start a food chain are called producers

(plants) known as a producer