Step 1: Active to passive.
Active: Subject (A surgeon) + modal (should) + verb (see) + object (him).
Passive: Object (He) + modal (should) + be + past participle (seen) + by subject (a surgeon).
Step 2: Checking options.
(A) Correct — "He should be seen by a surgeon."
(B) Wrong order.
(C) Wrong — changes meaning.
(D) Wrong structure.
Step 3: Conclusion.
Correct answer is (A) He should be seen by a surgeon.