Step 1: Understanding sulphapyridine.
Sulphapyridine is a type of sulfonamide antibiotic, used to treat bacterial infections. It works by inhibiting the growth of bacteria.
Step 2: Analyzing the options.
(A) Antibiotic: Correct — Sulphapyridine is an antibiotic.
(B) Tranquilizer: Incorrect — Sulphapyridine is not a tranquilizer.
(C) Antihistamine: Incorrect — It is not an antihistamine.
(D) Analgesic: Incorrect — Sulphapyridine is not an analgesic.
Step 3: Conclusion.
The correct answer is (A) Antibiotic, as sulphapyridine is used as an antibiotic.