Choose the idiom/phrase that can substitute the highlighted group of words meaningfully.
I have never seen someone so easily scared. She is so nervous.

Correct option is B

The correct idiom to substitute the highlighted phrase is Afraid of one's own shadow.
Afraid of one's own shadow: Extremely timid or nervous.
Example: She's so scared that she is afraid of her own shadow.
Similar idioms: Cowardly, Timid, Faint-hearted.