**Core Concept**
The plague is a zoonotic disease caused by the bacterium *Yersinia pestis*, transmitted primarily through the bites of infected fleas or direct contact with infected animals. The disease manifests in three main forms: bubonic, septicemic, and pneumonic.

**Why the Correct Answer is Right**
The correct answer is related to the fact that the plague is a significant public health concern due to its potential for person-to-person transmission. In pneumonic plague, the bacteria infect the lungs, causing a highly contagious and deadly form of the disease. This form of the plague can be transmitted between humans through respiratory droplets, making it a significant concern for public health officials.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the plague is not primarily spread through contaminated food or water. While poor sanitation and hygiene can contribute to the spread of the disease, the primary modes of transmission are through flea bites or direct contact with infected animals.

**Option B:** This option is incorrect because the plague is not a viral disease. *Yersinia pestis* is a gram-negative bacterium that causes the disease, not a virus.

**Option C:** This option is incorrect because the plague is not typically associated with a specific geographical region. While outbreaks have occurred in various parts of the world, the disease can occur anywhere where the bacteria and their vectors are present.

**Clinical Pearl / High-Yield Fact**
It's essential to recognize the signs and symptoms of plague, which can include fever, chills, weakness, and swollen lymph nodes (buboes). Prompt recognition and treatment are critical for preventing complications and death.

**Correct Answer: D. The pneumonic form of plague is highly contagious and can be transmitted between humans through respiratory droplets.**