What is ration of cow ?

The respiratory organ of cow is-

Which of the following is given to cow to yield milk?

Which of the following is needed for formation of biogas from cow dung?

A rhombus shaped field has green grass for 18 cows to graze. If each side of the rhombus is 30m and its longer diagonal is 48m, grass of how much area of grass field will each cow be getting ?