Correct Answer: I stepped forward and said to the storekeeper, "How much do the mangoes cost?"

Solution : The correct choice is the third option.

When transforming a sentence from indirect to direct speech, it's essential to ensure that the pronouns and verb tenses are adjusted appropriately.

The steps of the conversion are as follows:

• The reporting verb "asked" is changed to "said".
• There would be no change in the pronoun because there is no change in the person.
• The statement is changed to the question in the direct speech.
• The simple past tense is changed to the simple present tense.

Therefore, the direct form would be: I stepped forward and said to the storekeeper, 'How much do the mangoes cost?'