The increased nutrient absorption among animals fed antibiotics is thought to be linked to a. decreased incidence of disease. b. decreased illness. c. decreased ammonia in the gut. d. increased appetite.

The correct option is "C", "decreased ammonia in the gut". 
The increased nutrient absorption among animals fed antibiotics is thought to be linked to decreased ammonia in the gut.
Nutrient absorption is a procedure that organisms use to get supplements. Plants do this utilizing their their roots in the soil.In the body of an organism, the small small intestine is considered as the major digestive related organ, mostly all absorption happens there.