Select the most appropriate option to substitute the bracketed segment the given sentence. If there is no need to substitute it, select 'no substitution required' .
The unit twitched like a bird [preening it's plumage and becomes motionless).

A

preening its plumage and became motionless

B

No substitution required

C

preening it's plumage while becoming motionless

D

to preen it's plumage and becomes motionless