The correct option is C.
Isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. Isotopes have different relative atomic mass but share the same chemical properties.
The primary distinction between the digestive systems of cows and humans is that the former uses a foregut fermenter while the latter uses a straightforward monogastric digestion. The types of teeth, mouths, stomachs, guts, and digestive enzymes released by the gut also vary between the two digestive systems. Cows and humans have different digestive systems because they have evolved two different sorts of dietary patterns based on their capacities. The primary distinctions between the digestive systems of cows and humans are in the types of teeth, mouths, stomachs, and intestines, as well as the enzymes released.