Correct Answer: The supervisor asked the worker how long he had been working for that company.

Solution : The fourth option is the correct choice.

The given sentence is in direct speech. As per the given question, we have to change it into indirect speech. The process of transformation is as follows:

• The reporting verb "said to" is changed to "asked".
• "How" is used as a conjunction because we know that if the reported speech is interrogative with the question word, then the question word itself becomes the conjunction.
• The second-person pronoun "you" is changed into the third-person pronoun "he".
• The present perfect continuous tense "have been working" is changed to the past perfect continuous tense "have been working".
• "This" is changed to "that".
• The words of the speaker are enclosed in the inverted commas.

Therefore, the correct answer is: " The supervisor asked the worker how long he had been working for that company ."