Gardeners often put garden debris and dead plants in a compost pile where optimal conditions for decomposers encourage the breakdown of the debris into compost that can be used to fertilize the garden. The temperature of a healthy compost pile is generally between 90 and 140 degrees Fahrenheit. Why

Energy is released in the form of heat during decomposition

Explanation:

Decomposition, which is a process by which organic material is broken down by decomposers to form humus, leads to the release of nutrients an also energy. Most of the energy that is released during the decomposition of organic material is in the form of heat, which is lost in the process. Hence, the temperature that is observed in a healthy compost pile.

do you have a picture?

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.