The correct option is A Both assertion and reason are true, and the reason is the correct explanation of the assertion
Agricultural science includes an overall development of crop production and livestock (farm animals).
Animal husbandry deals with the care and breeding of livestock like buffaloes, cows, pigs, horses, cattle, etc. that are useful to humans. It includes poultry farming and fisheries.
As animal husbandry includes the development of the livestock which is a part of agricultural science the reason is the correct explanation of the assertion.