Q. Change into direct form: I said to him, “How do you know this?”

The correct answer is: (B) I asked him how he knew that.

Explanation:

The original sentence is in direct speech, and the question is asking for its indirect form.

1. The reporting verb “said to” changes to “asked” because the sentence is a question.

2. The question word “How” remains unchanged in indirect speech.

3. The pronoun “you” changes to “he” to match the subject of the reporting clause (“him”).

4. The verb “do know” changes to “knew” to reflect the backshifting of tense in indirect speech.

Thus, the correct indirect form is: “I asked him how he knew that.”