## Core Concept
The capsule of *Bacillus anthracis* is a critical virulence factor that helps the bacterium evade the host's immune system. The capsule is made of a specific type of polysaccharide.

## Why the Correct Answer is Right
The capsule of *Bacillus anthracis* is formed of **poly-D-glutamic acid**, which is a unique feature of this bacterium. This capsule is crucial for its pathogenicity as it prevents phagocytosis by host immune cells. The poly-D-glutamic acid capsule is also the target for specific diagnostic tests.

## Why Each Wrong Option is Incorrect
* **Option A:** This option is incorrect because the capsule is not made of a typical polysaccharide like those found in many other bacteria.
* **Option B:** This option is incorrect as it does not accurately describe the composition of the *B. anthracis* capsule.
* **Option C:** This option might seem plausible but is incorrect because the capsule is specifically made of poly-D-glutamic acid, not a combination or different type of molecule.
* **Option D:** This option is incorrect because it does not accurately represent the composition of the *B. anthracis* capsule.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the capsule of *Bacillus anthracis* is made of **poly-D-glutamic acid**, which is a distinguishing feature used in laboratory identification of the bacterium. This is crucial for diagnosing anthrax infections.

## Correct Answer Line
**Correct Answer: B. poly-D-glutamic acid**