A sentence is in active voice when the subject is the doer of the action.
A sentence is in passive voice when the new subject (object in active voice) is the receiver of that action.
The object in the active voice now takes the place of the subject, and vice versa. (subject + verb + object, where the subject and object swap places)
The given sentence is an imperative sentence (order or command). Hence in such sentences, the subject is merely implied.
The general structure of a negative imperative sentence in passive voice is:
let + object + not + be + participle.
Option A: The sentence follows the same structure
let + object (me) + not + be + past participle (misunderstood)
Hence option A is correct.
Option B: This sentence does not follow the general structure.
Moreover, 'should' in "shouldn't be misunderstood" refers to obligation, and not command. Hence B is incorrect.
Option C is incorrect because the given sentence is an order and not a requested: "you are not requested..."
Option D is incorrect because the sentence is incomprehensible: "You be not..."