**Core Concept**
Pseudomonas infections are often opportunistic, taking advantage of compromised host defenses. However, there are some exceptions where Pseudomonas can cause disease in healthy individuals.

**Why the Correct Answer is Right**
Pseudomonas aeruginosa can cause disease in healthy individuals through a process called "colonization factor antigen" (CFA), which helps the bacteria adhere to the host's respiratory epithelium. This is particularly relevant in the context of **pulmonary colonization**. In addition, some individuals may be more susceptible to Pseudomonas infections due to **genetic predisposition**, such as those with cystic fibrosis.

**Why Each Wrong Option is Incorrect**
**Option A:** Not applicable, as this option is missing.
**Option B:** Not a specific exception to the opportunistic nature of Pseudomonas infections.
**Option C:** Not a well-documented exception to the opportunistic nature of Pseudomonas infections.

**Clinical Pearl / High-Yield Fact**
Pseudomonas aeruginosa is a notorious pathogen that can cause disease in healthy individuals through colonization factors, making it a significant concern in healthcare settings.

**Correct Answer: D. This option is missing in the original question.