Rewrite the sentence in the passive voice.
My sister has painted this wall.

Correct option is A

The correct option is (a) This wall has been painted by my sister.
Definition of Active Voice: In active voice, the subject of the sentence performs the action.
Definition of Passive Voice: In passive voice, the subject of the sentence receives the action.
Tense identification: The sentence is in Present Perfect Tense.
Rule: In Present Perfect Tense, the structure for changing active to passive is:
Active voice: Subject + has/have + V3 + Object.
Passive voice: Object + has/have + been + V3 + by + Subject.
Corrected sentence: This wall has been painted by my sister.