It was at first impossible for any one to realize what had actually happened. The smoke and fumes hid everything from sight, and hundreds of men were thrown into a comatose or dying condition, and within an hour the whole position had tcibe abandoned, together with about fifty guns.

$-$British Field Marshal Sir John French, report on the second battle of Ypres, $1915$

What caused the scene described in this excerpt?

A A tank attacking soldiers on a battlefield

B An aerial bombing of an infantry unit

C A poison gas attack on soldiers in the trenches

D A submarine attacking a docked ship