Question

this
house was.........my grandfather?
a)built by
b)built for

Answer 1

This house was built by my grandfather

Answer 2

ANSWER:

This house was built by my grandfather

Or we can also say

This house was built for my grandfather

EXPLANATION:

   For and ‘by’ are prepositions, where a preposition is utilised to connect nouns, phrases or pronouns, or words in a sentence, that is, connecting people, time, locations and objects of a sentence.

   The first option using the preposition ‘by’ in the sentence: By implies who or what performed/did the action (someone or something). This preposition is used in a passive sentence indicating “WHO” is doing or performing the action. In the above sentence ‘by’ implies that the house was built ‘by’ the grandfather, where ‘grandfather’ is the one doing/performing the action

   The second option using the preposition ‘for’ in the sentence: ‘For’as a preposition is used to denote ‘with the purpose of objective of’. In the above sentence ‘for’ implies building the house ‘for’ the grandfather, where ‘grandfather’ is the purpose or objective.