Question

methanogens help break down the tough carbohydrate _. a cellulose b starch c glucose d glycogen

Explanation:

Methanogens are involved in the anaerobic digestion of complex carbohydrates. Cellulose is a tough, fibrous carbohydrate that can be broken - down by methanogens in certain environments like the rumen of ruminants or anaerobic digesters. Starch is more easily digestible compared to cellulose, glucose is a simple sugar, and glycogen is a storage polysaccharide in animals.

Answer:

a. cellulose