Select the most appropriate option to fill in the blank and make a grammatically correct sentence.

Rachna was angry with her father because he did not take her to the zoo as he ______.

had promised

The most appropriate option to fill in the blank is had promised.

The sentence is about how Rachna was angry with her father because he did not take her to the zoo as he had promised to do. The past perfect tense is used to indicate that the action of promising happened before the action of not taking Rachna to the zoo.

The other options are not as appropriate.

• The simple present tense "promise" does not make sense because the action of promising happened in the past.
• The present progressive tense "promises" does not make sense because the action of promising is not happening now.
• The simple future tense "is promising" does not make sense because the action of promising has already happened.