**Core Concept**
Pseudomonas aeruginosa is a Gram-negative bacterium that thrives in moist environments, particularly in water-based settings. This organism is known to cause opportunistic infections, especially in individuals with compromised immune systems or those exposed to contaminated water sources.

**Why the Correct Answer is Right**
A lifeguard in a swimming pool is at risk of developing Pseudomonas aeruginosa infection due to the organism's presence in contaminated water. Pseudomonas aeruginosa can colonize and multiply in the biofilm on water surfaces, where it can be aerosolized, creating a risk of infection for individuals who breathe in these contaminated droplets. This is particularly concerning for individuals with compromised immune systems, such as those with cystic fibrosis or chronic lung disease.

**Why Each Wrong Option is Incorrect**
**Option B:** A poultry worker is more likely to be exposed to avian pathogens such as Salmonella or Campylobacter, which are commonly associated with poultry-related illnesses.
**Option C:** A farmer may be exposed to various pathogens through contact with animal waste, but they are not specifically at risk for Pseudomonas aeruginosa infections.
**Option D:** A kennel worker may be exposed to zoonotic pathogens such as Leptospira or E. coli, which are commonly associated with animal contact, but they are not specifically at risk for Pseudomonas aeruginosa infections.

**Clinical Pearl / High-Yield Fact**
Pseudomonas aeruginosa is a notorious healthcare-associated pathogen that can cause severe infections in immunocompromised individuals. It is essential for healthcare workers to be aware of the risks associated with contaminated water sources and to take appropriate precautions to prevent the spread of this organism.

**✓ Correct Answer: A. A lifeguard in swimming pool**