Most fungi are saprobes. what does this mean?
they feed on dead and decaying organic matter.
they can prepare their own food.
they live in a mutually beneficial relationship

Option A, They feed on dead and decaying organic matter.

Explanation:

Group of fungi that act as decomposers and feed upon dead , rotting  and decaying organic matter such as litter, dead bodies, dead parts of plants and animals etc.

In order to digest decaying organic food, these organism releases enzymes in  order to break it down into simpler molecules. In this way organic waste is removed and vital nutrients are released for other organisms

Hence, option A is correct