Which organism is the producer in the following food chain?
plant> caterpillar> lizard> snake

the answer is plant because it produces it's own food source, and is also provides nourishment for herbivores and other animals.

A. Plant

Explanation:

A producer is any organism that serves as a source of food for other organisms in a food chain, such as plants. With the definition of Producer in mind we can then understand that a caterpillar is a consumer and a lizard is a insectivore and/or carnivore and a snake is a carnivore, this leaves a plant as a producer.