In Animal science the term Stag refers to:

Correct option is A

The correct answer is (a). In Animal science the term Stag refers to Castrated male of Pig.
Different terms are used for castrated males of different species:
(a) Castrated male of Pig: Referred to as a “stag.”
(b) Castrated male of Horse: Known as a “gelding.”
(c) Castrated male of Goat: Called a “wether.”
(d) Castrated male of Sheep: Also termed a “wether.”
(e) Castrated male of Cow: Referred to as a “steer.”