**Core Concept**
Pseudomembranous colitis, also known as Clostridioides difficile (C. difficile) infection, is a type of antibiotic-associated diarrhea caused by the overgrowth of C. difficile bacteria in the colon. This condition typically occurs after the use of broad-spectrum antibiotics, which disrupt the normal gut flora.

**Why the Correct Answer is Right**
The development of pseudomembranous colitis in this patient is likely due to the disruption of the normal gut flora by the antibiotic treatment. C. difficile produces toxins A and B, which cause inflammation and damage to the colon mucosa, leading to the formation of pseudomembranes. The antibiotics that are commonly associated with C. difficile infection include clindamycin, cephalosporins, fluoroquinolones, and penicillins.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because clindamycin is a well-known antibiotic that is commonly associated with C. difficile infection.
**Option B:** This option is incorrect because cephalosporins are a class of antibiotics that can also disrupt the normal gut flora, leading to C. difficile overgrowth.
**Option C:** This option is incorrect because fluoroquinolones are broad-spectrum antibiotics that can also contribute to C. difficile infection.
**Option D:** This option is incorrect because penicillins are a class of antibiotics that can also disrupt the normal gut flora, leading to C. difficile overgrowth.

**Clinical Pearl / High-Yield Fact**
To prevent C. difficile infection, it is essential to use antibiotics judiciously and only when necessary. Additionally, the use of probiotics or other agents that promote the growth of beneficial gut flora may also help to prevent C. difficile overgrowth.

**Correct Answer: D. Penicillins are less commonly associated with C. difficile infection compared to other antibiotics, but they can still contribute to its development.