Question

what is peat?
hardened magma
partially decayed plant matter
compressed sand
fully formed coal

Explanation:

Peat is formed from partially decayed plant matter in waterlogged conditions over thousands of years. Hardened magma refers to igneous rocks, compressed sand can form sandstone (sedimentary rock), and fully - formed coal is a more processed fossil fuel than peat.

Answer:

Partially decayed plant matter