Select the correct indirect form of the given sentence. Nandini said, “I bought a pen yesterday.”

Nandini said that she had bought a pen the previous day.

The correct indirect form of the given sentence is:

Nandini said that she had bought a pen the previous day.

The other options are incorrect:

• Nandini said she did bought a pen the previous day. - This is incorrect because the modal verb "did" is unnecessary in this context.
• Nandini said that she had bought a pen yesterday. - This is incorrect because the adverb "yesterday" in the reported speech is in the present tense, but the reporting verb "said" is in the past tense.
• Nandini says that she had bought a pen the previous day. - This is incorrect because the reporting verb "says" is in the present tense, but the reporting event took place in the past.