The correct option is C Let the papers be shown.
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 an imperative sentence in passive voice is:
let + object + be + participle.
Option C: The sentence follows the same structure
let + object (the papers) + be + past participle (shown)
Hence option C is correct.
Option A: This sentence does not follow the general structure. The object 'the papers' must precede the passive verb 'be shown'.
Option B: This sentence does not have a complete meaning.
Option D: The given sentence is an order and not a suggestion (It is suggested).
Hence options A, B and D are incorrect.