The largest reservoir of sulphur in the biosphere is the

Answer: Option D

The largest reservoir of sulphur in the biosphere is the Rocks.
Sulphur may be found by itself and historically was usually obtained in this form; pyrite has also been a source of sulphur. Sulphur deposits were piled and stacked in brick kilns built on sloping hillsides, with airspaces between them.
Mining was unmechanized and labor-intensive, with pickmen freeing the ore from the rock, and mine-boys carrying baskets of ore to the surface, often through a mile or more of tunnels.