In the sentence "The doctor phoned the nurse because she was late," the pronoun "she" is ambiguous - it could refer to either the doctor or the nurse.

Without additional context, we cannot definitively determine who was late. The sentence could mean:
- The doctor phoned the nurse because the nurse was late
- The doctor phoned the nurse because the doctor was late (perhaps to inform the nurse of the delay)

This is a classic example of pronoun ambiguity in English, where the antecedent of "she" is unclear.
