The given sentence is in active voice. Change the voice of the sentence. Select the correct option from the sentences given in options.

I know he will play his guitar.

It is known to me that his guitar will be played by him.

The correct passive voice of the sentence I know he will play his guitar is It is known to me that his guitar will be played by him.

The active voice of the sentence is I know he will play his guitar. This sentence is in the simple present tense, which is used to describe an action that happens regularly or always happens. The passive voice of the sentence is formed by putting the subject of the active sentence after the verb "to be" and the past participle of the main verb. In this case, the subject of the active sentence is "I" and the main verb is "know." The past participle of "know" is "known." So, the passive form of the sentence is It is known to me that his guitar will be played by him.

The other options are incorrect because:

• His guitar will be played by him is something I know. is in the active voice of the sentence, but the subject of the sentence is incorrect. The guitar will be played by him, not something I know.
• It is known to me that his guitar would be played by him. is in the past tense, while the original sentence is in the present tense.
• His guitar will be played by him is know to me. is grammatically incorrect. The verb "to be" needs to be in the past participle form, which is "known."