Which of these corrects the shift of voice in the following sentence?
nakamura was praying for protection when the front door was flung open by force.
nakamura was praying for protection when the front door was flung open by the police.
a prayer for protection was being said by nakamura when a force flung the front door open.
nakamura was praying for protection when a force flung the front door open.
a prayer for protection was being said by nakamura when the police flung the front door open.

Option B, A prayer for protection was being said by Nakamura when a force flung the front door open.

Explanation:

A shift in voice of a sentence or statement is considered when there is a change in the tense, person and voice of the  sentence or statement.

Here the given statement is in active voice and in the option chosen the voice is passive. Here the voice is changing from active to passive which is the requirement of producing a shift in voice , thus, option B is correct.

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