The answer is:
A) Cells are the basic unit of life.
Coal seams are far deep underground to be considered for opencast minings. These coal seams require underground mining. Since it is too deep underground, it can be used for mapping and correlation of sedimentary rocks or as a key bed.
The cell would have 2 nuclei but the cytoplasm wouldn't be able to split.
Because less animals means less energy that can be used.