An action in a sentence can be represented in two ways, namely active and passive voice.

The passive voice always uses the past participle form of the main verb irrespective of any tense. Only the auxiliary verb depends upon the sentence given in the active voice.

The correct answer is C)Let this be done by me.

Option C is correct as the subject of the given sentence (you- it is understandable that the speaker is speaking to someone in front of him) comes in the place of the object (me) and vice versa, the same tense is used (simple present tense), 'be' is used with the past participle of the main verb(do).