**Core Concept**
Pseudomembranous colitis, also known as Clostridioides difficile (C. difficile) colitis, is a gastrointestinal infection caused by the toxin-producing bacterium C. difficile. This condition often arises after the use of broad-spectrum antibiotics, which disrupt the normal gut microbiota and allow C. difficile to overgrow.

**Why the Correct Answer is Right**
C. difficile produces two primary toxins, toxin A and toxin B, which cause inflammation and damage to the intestinal lining, leading to pseudomembranous colitis. The toxins work by activating the host's inflammatory response and disrupting the tight junctions between intestinal epithelial cells, resulting in fluid and electrolyte loss, abdominal pain, and diarrhea.

**Why Each Wrong Option is Incorrect**
**Option A:** This statement is true. Pseudomembranous colitis can indeed be caused by the use of broad-spectrum antibiotics, which disrupt the normal gut microbiota and allow C. difficile to overgrow.
**Option B:** This statement is true. Pseudomembranous colitis is characterized by the presence of pseudomembranes, which are yellowish or whitish patches on the surface of the colon.
**Option C:** This statement is false. Pseudomembranous colitis is not typically caused by viral infections, but rather by bacterial overgrowth, particularly C. difficile.

**Clinical Pearl / High-Yield Fact**
To prevent C. difficile colitis, it is essential to use antibiotics judiciously and to ensure proper hand hygiene and infection control practices in healthcare settings. Additionally, the use of probiotics may help maintain a healthy gut microbiota and reduce the risk of C. difficile infection.

**Correct Answer: C. C. difficile colitis is not typically caused by viral infections.**