Question

my father will retire from service _____an year

Answer 1

My father will retire from service in an year

Answer 2

Answer:

My father will retire from service in an year is the correct answer.

Explanation:  

In is a preposition of time. A preposition is a word preceding a ‘noun or pronoun’. It is expressed in ‘relation to another’ word or clause. It can be said that it is a word . That joins two sentences. Prepositions can be prepositions of place, prepositions.  Of time, prepositions of direction and prepositions of agent.