She heard the phone ___ and went to the first floor to answer it.a) rangb) to ringc) is ringingd) ringing

To determine the correct answer for the sentence "She heard the phone ___ and went to the first floor to answer it," we need to analyze each option.

1. Option A: rang - This is the simple past tense of "ring." It fits well in the sentence, indicating that the action occurred in the past.

2. Option B: to ring - This form is an infinitive and does not work in this context as it suggests a future action rather than a completed action.

3. Option C: is ringing - This present continuous form indicates an ongoing action but does not align well with "heard," which implies that the ringing was already completed.

4. Option D: ringing - This present participle form could work to suggest a continuous action but is less conventional in this context since it would typically require additional context.

Conclusion:

The best fit for the sentence is option A: rang.

Final Answer:

She heard the phone rang and went to the first floor to answer it.