**Core Concept**
The cell wall of Bacillus anthracis is a complex structure composed of peptidoglycan and other components, which provides rigidity and structural integrity to the bacterium. The unique composition of the Bacillus anthracis cell wall is a key factor in its pathogenicity and virulence.

**Why the Correct Answer is Right**
The cell wall of Bacillus anthracis is primarily composed of a thick layer of peptidoglycan, also known as murein, which is a polymer of N-acetylglucosamine and N-acetylmuramic acid. This peptidoglycan layer is responsible for the bacterium's resistance to osmotic pressure and provides structural support to the cell. In addition to peptidoglycan, the Bacillus anthracis cell wall also contains teichoic acids, which are linked to the peptidoglycan layer and play a role in cell division and cell wall synthesis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the composition of the Bacillus anthracis cell wall.
**Option B:** This option is incorrect because it is not a component of the Bacillus anthracis cell wall.
**Option C:** This option is incorrect because it is a component of the Gram-negative cell wall, not the Bacillus anthracis cell wall.

**Clinical Pearl / High-Yield Fact**
The Bacillus anthracis cell wall is resistant to lysozyme, an enzyme that breaks down peptidoglycan in the host's immune system, allowing the bacterium to survive and proliferate in the host.

**Correct Answer:** D.