**Core Concept**
Meningococcal meningitis is a severe and potentially life-threatening infection caused by the bacterium Neisseria meningitidis. Prophylaxis involves administering a medication to prevent the spread of the disease, particularly in close contacts of an infected individual.

**Why the Correct Answer is Right**
Rifampicin (or rifampin) is a broad-spectrum antibiotic that is effective against Neisseria meningitidis. It is commonly used for prophylaxis in close contacts of individuals with meningococcal meningitis, as it can eradicate the bacteria from the nasopharynx, thereby preventing transmission. Rifampicin works by inhibiting RNA synthesis through its action on beta-subunit of bacterial RNA polymerase.

**Why Each Wrong Option is Incorrect**
**Option A:** Ciprofloxacin is a fluoroquinolone antibiotic, but it is not typically used for prophylaxis of meningococcal meningitis. Its use is more common in the treatment of other bacterial infections.
**Option B:** Ceftriaxone is a cephalosporin antibiotic effective against a wide range of bacterial infections, including meningitis. However, it is not used for prophylaxis of meningococcal meningitis.
**Option C:** Amoxicillin is a penicillin antibiotic commonly used to treat various bacterial infections, but it is not effective against Neisseria meningitidis and is therefore not used for prophylaxis of meningococcal meningitis.

**Clinical Pearl / High-Yield Fact**
Rifampicin is known to cause a harmless but unpleasant discoloration of bodily secretions, such as urine, sweat, and saliva, which can stain clothing and other materials. This is a common side effect of the medication and should not be confused with any underlying medical condition.

**Correct Answer:** C. Rifampicin