**Core Concept**
Meningococcal infection, caused by Neisseria meningitidis, is a severe and potentially life-threatening bacterial infection that requires prompt and effective treatment. The treatment of choice involves a combination of antibiotics and supportive care to manage symptoms and prevent complications.

**Why the Correct Answer is Right**
The treatment of choice for meningococcal infection is ceftriaxone, a third-generation cephalosporin antibiotic that has broad-spectrum activity against Neisseria meningitidis. Ceftriaxone works by inhibiting cell wall synthesis in the bacteria, ultimately leading to bacterial lysis and death. It also has good penetration into the cerebrospinal fluid, making it effective in treating meningitis. The recommended dose is typically 2 grams IV every 12 hours for 7-10 days.

**Why Each Wrong Option is Incorrect**
**Option A:** Penicillin G is not the preferred treatment for meningococcal infection because it is not as effective as ceftriaxone against this particular bacteria. Although penicillin G is still used in some cases, ceftriaxone is generally considered the treatment of choice due to its broader spectrum of activity and better penetration into the cerebrospinal fluid.

**Option B:** Vancomycin is not typically used as a first-line treatment for meningococcal infection, although it may be used in combination with ceftriaxone in certain cases, such as in patients with a history of penicillin-resistant Neisseria meningitidis or in patients with a severe penicillin allergy.

**Option C:** Rifampin is an antibiotic used to prevent the spread of meningococcal infection to close contacts, rather than to treat the infection itself. It is often administered to family members, friends, and other individuals who have been in close contact with someone diagnosed with meningococcal infection.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that meningococcal infection can progress rapidly, and early recognition and treatment are critical to preventing complications and improving outcomes. Always consider meningococcal infection in the differential diagnosis of patients presenting with fever, headache, and stiff neck, particularly in the setting of a severe bacterial infection.

**Correct Answer:** C. Ceftriaxone