Final answer:
The correct answer is c) Cud. Cows, as ruminants, regurgitate partially digested food known as cud, which they chew again to further break down cellulose with the help of microbes in their stomachs.
Step-by-step explanation:
Ruminate on this--it's what a cow chews the second time around. The correct answer to what a cow chews the second time around is c) Cud. The process of ruminating involves several steps. Initially, food is chewed in the mouth, then passes through the esophagus into the rumen and then the reticulum. These first two chambers contain microbes that break down cellulose and ferment the ingested plant material. The ruminant then regurgitates the cud from the rumen, chews it, and swallows it into the third chamber, the omasum, which removes water. Finally, the cud enters the fourth stomach, the abomasum, where it is digested by enzymes. This efficient digestive process allows ruminants like cows to extract nutrients from plant-based foods that other animals cannot digest as easily.