**Core Concept**
Pseudomembranous colitis, also known as Clostridioides difficile (C. difficile) colitis, is a type of diarrhea caused by an imbalance of gut microbiota, often resulting from antibiotic use. The condition is characterized by the formation of a pseudomembrane in the colon.

**Why the Correct Answer is Right**
Clindamycin is a lincosamide antibiotic that is known to disrupt the normal gut flora, leading to an overgrowth of C. difficile. This bacterium produces toxins that cause the symptoms of pseudomembranous colitis. The mechanism of clindamycin-induced pseudomembranous colitis involves the inhibition of protein synthesis in susceptible bacteria, allowing C. difficile to outcompete and overgrow the normal gut flora.

**Why Each Wrong Option is Incorrect**
**Option A:** Not applicable (no information provided)
**Option B:** Not a commonly associated antibiotic with pseudomembranous colitis
**Option C:** Not a well-documented cause of pseudomembranous colitis
**Option D:** Not a commonly used antibiotic that disrupts gut flora

**Clinical Pearl / High-Yield Fact**
When prescribing antibiotics, it's essential to consider the potential for disrupting the normal gut flora and the risk of developing C. difficile colitis. This can be mitigated by using the narrowest effective spectrum of antibiotics, monitoring patients for signs of diarrhea, and considering prophylactic measures such as probiotics.

**Correct Answer: A. Clindamycin**