What is the source of coal formation?

Plants

The correct answer is option 1. Plants.

The source of coal formation is primarily Plants.

Coal is a fossil fuel formed from the remains of ancient plants that lived millions of years ago. These plants died and were buried under layers of sediment. Over time, the immense heat and pressure from these layers caused the plant matter to decompose and transform into coal.

While some animals may have been incidentally incorporated into coal deposits, plants are the dominant source material.