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 verbs depend upon the sentence given in active voice.

The correct answer is B)It has been stolen..

The option B is correct as the given sentence is in active voice and to transform it into passive voice , the subject of the given sentence (the car) comes in the place of the object(it) and vice versa. Also, as the sentence is in the present perfect tense, 'been' is added after the helping verb 'has' and before the past participle form of the main verb(steal).

Options A,C, and D are wrong as is, was and had been cannot be used respectively.