Answer: idiom
Explanation: assuming she didn't straight up die on the spot, she didn't literally stop dead in her tracks, so it would be an idiom
it can't be an alliteration since the words don't start with the same letter (or close). there's no sound effect so it can't be onomatopoeia. there's nothing standing in place of a subject (ex. he is my rock, she's a smart cookie, school is prison, etc.) so it can't be a metaphor
