CORRECT answer is Medicines should not be bought without the doctor's prescriptionImperative sentences are sentences that express advice, request, or command.There are some sentences which contain suggestion.Let’s see how to convert these sentences into PASSIVE by some examples.Ex:Respect parents. (ACTIVE Voice)Parents should be respected. (Passive Voice)Love the kids. (Active Voice)The kids should be loved. (Passive Voice)FOLLOW your DREAMS. (Active Voice)Your dreams should be followed. (Passive Voice)Thus, we use 'should' in imperative sentences in passive sentences containing 'suggestion'.While changing from active to passive voice, we change the subject to the object and vice versa. Thus, the object 'Medicines' will become the subject in passive voice.At Last lining up the remaining sentence: without the doctor's prescription. Thus, the sentence becomes: Medicines should not be bought without the doctor's prescription