Meat and animal products for human consumption come mainly from terrestrial animal species.
a. 30
b. 15
c. 21
d. 8

A.  30 %

Explanation:

As there are 6.5 million species on land and 2.2 million in water i.e around 25 % of species including 5 % of freshwater species in oceans, thus the 80% of species on earth make up most of the terrestrial animal composition of meat and other animal products like beef, pork, chicken and other land and animals found in mountains , plains and plateaus they maybe either in Arid, semi arid and desert regions.