**Core Concept:** Cutaneous anthrax is a skin infection caused by the bacterium Bacillus anthracis. The infection primarily affects animals, but can also infect humans through contact with infected animals or their products, or contaminated soil or water. Anthrax spores can germinate into bacteria within macrophages, leading to systemic infection if not treated promptly.

**Why the Correct Answer is Right:**

The correct answer, D, is right because anthrax is primarily a skin infection in animals and humans. It is caused by the bacterium Bacillus anthracis. When anthrax spores come into contact with the skin or mucous membranes, they can germinate into bacteria within macrophages, which leads to cutaneous anthrax. Inhalational anthrax occurs when spores are inhaled, and ingestional anthrax occurs when spores are ingested.

**Why Each Wrong Option is Incorrect:**

A. Anthrax is primarily cutaneous in nature, making this statement incorrect.
B. Inhalational anthrax is due to inhalation of spores, not ingestion.
C. Ingestional anthrax is due to ingestion of spores, not intoxication.

**Clinical Pearl / High-Yield Fact:**

When treating cutaneous anthrax, appropriate antibiotics (such as doxycycline or ciprofloxacin) must be administered early to prevent the bacteria from germinating within macrophages and causing systemic infection. Prompt diagnosis and treatment can significantly improve patient outcomes.

**Correct Answer:**

D. Ingestional anthrax

Answer: Ingestional anthrax is caused by ingesting contaminated food or water, while cutaneous anthrax and inhalational anthrax are caused by coming into contact with contaminated animal fur, soil, or water. Anthrax spores can germinate and cause systemic infection if not treated promptly.