Select the most appropriate passive form of the verb to fill in the blank in the given sentence:
By this time next week, the sound track of the film ___ remixed by the sound technician.

Correct option is D

The correct passive form is option (d) would have been.

Correct Passive Sentence:
By this time next week, the sound track of the film would have been remixed by the sound technician.

Explanation:
The time expression By this time next week indicates a future point by which an action will have been completed. This calls for the Future Perfect Tense. In passive voice, the Future Perfect Passive is formed as follows:

Grammatical Rule Used (English):

• Active Future Perfect: Subject + will have + V³ + object
• Passive Future Perfect: Object + would have been + V³ + by + subject

• (a) had been – Past perfect passive; refers to a past time, not a future time. Incorrect.
• (b) is being – Present continuous passive; refers to an ongoing action in the present. Incorrect.
• (c) has been – Present perfect passive; refers to a recently completed action. Incorrect for a future time expression.