Select the most appropriate option to substitute the highlighted phrase in the given sentence.
The boy watched a sci-fi movie in the lieu of playing in the game zone.

Correct option is D

Explanation:
The correct idiomatic expression is “in lieu of”, which means “instead of”, and it should be followed by a gerund (playing).
(a) on lieu of – Incorrect preposition
(b) in lieu off – “off” is a spelling error; incorrect preposition
(c) in lieu of play – “Play” is a noun here, but the gerund “playing” fits grammatically and idiomatically
Grammar Rule:
“In lieu of” is a fixed prepositional phrase used with gerunds or nouns.
Example: She worked overtime in lieu of taking a holiday.