**Core Concept**
MRSA (Methicillin-resistant Staphylococcus aureus) infection is a type of bacterial infection caused by a Staphylococcus aureus strain that is resistant to beta-lactam antibiotics, including methicillin and other penicillins. Effective treatment of MRSA infection requires the use of alternative antibiotics.

**Why the Correct Answer is Right**
The correct answer is Vancomycin, which is a glycopeptide antibiotic that is effective against MRSA. Vancomycin works by inhibiting the synthesis of the bacterial cell wall, ultimately leading to cell lysis and death. It is commonly used to treat serious MRSA infections, including bacteremia and endocarditis.

**Why Each Wrong Option is Incorrect**
**Option A:** Trimethoprim/Sulfamethoxazole (TMP/SMX) - While TMP/SMX is effective against some types of bacterial infections, it is not typically used to treat MRSA infections due to resistance. MRSA is often resistant to sulfonamides, including TMP/SMX.
**Option B:** Ciprofloxacin - This fluoroquinolone antibiotic is not typically effective against MRSA due to widespread resistance. MRSA has developed resistance to many antibiotics, including fluoroquinolones.
**Option C:** Clindamycin - Clindamycin is a lincosamide antibiotic that can be effective against MRSA, particularly in skin and soft tissue infections. However, it is not a first-line treatment and should be used with caution due to potential resistance and side effects.

**Clinical Pearl / High-Yield Fact**
When treating MRSA infections, it's essential to consider the local epidemiology and resistance patterns, as well as the specific infection site and severity. Vancomycin remains a cornerstone of MRSA treatment, but other antibiotics, such as linezolid and daptomycin, may also be effective in certain situations.

**Correct Answer: B. Ciprofloxacin.**