**Core Concept**
Tetanus is a bacterial infection caused by Clostridium tetani, characterized by muscle rigidity, spasms, and lockjaw. The pathogenesis involves the production of tetanospasmin, a potent neurotoxin that interferes with neurotransmitter release.

**Why the Correct Answer is Right**
The correct answer is related to the mechanism of action of tetanospasmin, which blocks the release of neurotransmitters glycine and GABA in the central nervous system. This results in an increase in excitatory neurotransmitter release, leading to muscle rigidity and spasms. Tetanospasmin specifically targets the inhibitory neurotransmitter release, causing an imbalance in neurotransmitter activity.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately describe the mechanism of tetanus infection.
**Option B:** This option is incorrect as tetanus is not caused by a viral infection.
**Option C:** This option is incorrect as it does not accurately describe the pathogenesis of tetanus.

**Clinical Pearl / High-Yield Fact**
It's essential to note that tetanus infection can occur through contaminated wounds, especially those with dirt or debris. Tetanus immunization is crucial, especially for individuals with a history of traumatic injuries or those working in high-risk environments.

**Correct Answer: B. Tetanus is caused by Clostridium tetani, a gram-positive bacterium.**