A bog is a wetland that...

A) is entirely covered with thick floating mats of vegetation

B) has shallow water and tall grass like plants

C) has shallow water and Woody shrubs and trees

D) has mostly salt water

(please no guesing)

A) is entirely covered with thick floating mats of vegetation

Explanation:

The bog vegetation, mostly sphagnum moss anchored by sedges (such as Carex lasiocarpa), forms a floating mat approximately half a meter thick on the surface of the water or on top of very wet peat.