Cellulose Is One of the Most Abundant Organic Molecules in the Biosphere

Cellulose is one of the most abundant organic molecules in the biosphere, but most animals lack the enzymes needed to break it down. Nevertheless, some animals have and can digest a diet high in cellulose because

A) cellulose provides essential fatty acids.
B) their microbial symbionts break it down, allowing them to obtain energy from cellulose indirectly.
C) cellulose is a required nutrient for microbial symbionts.
D) the only food supply available to them contains large amounts of cellulose.