The correct option is
D Was repaired
NOTE: The person who repaired the machine is not mentioned here. The action that is performed on the object, is made the subject of the sentence and hence the sentence is in the passive voice.
'Yesterday afternoon' explains that the sentence is in simple past tense.
We use 'was/were' and the verb is in the past participle form in the passive voice to form the sentence in the simple past tense.
Option B - 'Is repaired' can be used in the passive voice to form the sentence in the simple present tense. Hence, option B is incorrect.
Option C - 'Is being repaired' can be used in the passive voice to form the sentence in the present continuous tense. Hence, option C is incorrect.
Option D - 'Is repairing' can be used in the active voice to form the sentence in the present continuous tense. Thus option D is incorrect.
Option A - 'Was repaired' can be used in the passive voice here to form the sentence in the simple past tense. 'Was' can be used as the subject 'it' is singular and 'repaired' is the past participle form of the verb. Thus option A is the correct answer.
'The washing machine was broken but it's working now. It was repaired yesterday afternoon.'