Sentence improvement — idiom: 'take someone at their word' (accept what they say as true), not 'take her word': '… so I’ll have to take her at her word.'

Given sentence
She says she's already paid me back, but I can't remember, so I'll have to take her word.

Concept/Approach
The fixed idiom is take someone at their word. Another acceptable idiom is take someone's word for it, but the best direct completion here is 'take her at her word'.

Option analysis
• to take her at her word → standard idiom.• 'to take her word true' → unidiomatic.• 'to take her word for it' → also idiomatic but alters the original structure slightly; the prompt asks for the best fit.• 'No improvement' → incomplete idiom.

Final Answer
to take her at her word