Final answer:
Coal is formed from plant material that accumulates in anoxic depositional environments, which inhibits decomposition and allows the organic material to transform into peat and ultimately coal. The correct option is a.
Step-by-step explanation:
Coal forms from plant material that accumulates in a(n) anoxic depositional environment. The correct option is a) plant material/anoxic.
Coal, a type of fossil fuel, is predominantly derived from plant remains that were subjected to high temperatures and pressures after being buried hundreds of millions of years ago. The coal's formation process must occur in an environment lacking in oxygen, like swamps or bogs, to prevent the decomposition of the plant material.
Such anoxic conditions facilitate the partial decomposition of plant tissue which eventually turns into peat and, over time, is transformed into coal.