I think there's been a mistake. The subject/topic is not Anatomy, but rather Pharmacology/Microbiology. Here's the explanation:

**Core Concept**
Ceftazidime is a third-generation cephalosporin antibiotic effective against Pseudomonas aeruginosa, a Gram-negative bacterium. This antibiotic works by inhibiting cell wall synthesis in the bacterial cell wall.

**Why the Correct Answer is Right**
Ceftazidime has a broad spectrum of activity, including efficacy against Pseudomonas aeruginosa. It achieves this by binding to penicillin-binding proteins (PBPs) located inside the bacterial cell wall, thereby inhibiting the cross-linking of peptidoglycan layers. This ultimately leads to the death of the bacterial cell. Ceftazidime's effectiveness against Pseudomonas aeruginosa is particularly notable, as this bacterium often develops resistance to other antibiotics.

**Why Each Wrong Option is Incorrect**
**Option A:** Cefixime is a third-generation cephalosporin as well, but it lacks efficacy against Pseudomonas aeruginosa. Cefixime is primarily used to treat infections caused by Gram-negative bacteria, but its spectrum of activity does not include Pseudomonas.
**Option C:** Ampicillin is a penicillin antibiotic, which is generally ineffective against Pseudomonas aeruginosa. Pseudomonas bacteria often produce beta-lactamase enzymes that inactivate penicillins like ampicillin.
**Option D:** Cotrimoxazole (trimethoprim/sulfamethoxazole) is a combination antibiotic effective against a range of bacterial infections, but it is not the preferred treatment for Pseudomonas aeruginosa. While cotrimoxazole can be effective against some Gram-negative bacteria, it is not the first-line treatment for Pseudomonas infections.

**Clinical Pearl / High-Yield Fact**
When treating Pseudomonas infections, it's essential to use antibiotics that are specifically effective against this bacterium, such as ceftazidime or ciprofloxacin. Resistance to these antibiotics can develop rapidly, making it crucial to choose the most effective treatment option and monitor for resistance.

**✓ Correct Answer: B. Ceftazidime**