**Core Concept**
Tetanospasmin is the neurotoxin responsible for the clinical manifestations of tetanus. It is produced by the bacteria Clostridium tetani and acts as a potent inhibitor of presynaptic neurotransmitter release.

**Why the Correct Answer is Right**
Tetanospasmin exerts its effects by binding to specific receptors on the surface of neurons, which ultimately leads to the inhibition of the release of neurotransmitters such as glycine and GABA. This results in an increase in the excitability of motor neurons, leading to the characteristic rigidity and spasms seen in tetanus. The toxin also blocks the release of neurotransmitters involved in inhibitory neurotransmission, further contributing to the development of spasms.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because tetanospasmin does not directly stimulate the release of excitatory neurotransmitters. Instead, it acts by inhibiting the release of inhibitory neurotransmitters.
**Option B:** This option is incorrect because tetanospasmin does not directly interact with the postsynaptic receptor. Its effects are mediated through a complex series of biochemical events that ultimately lead to the inhibition of neurotransmitter release.
**Option C:** This option is incorrect because tetanospasmin does not directly affect the postsynaptic membrane's permeability to ions. Its effects are mediated through the inhibition of neurotransmitter release.

**Clinical Pearl / High-Yield Fact**
Tetanus toxin can remain viable for extended periods in the environment, making it a significant public health concern. The toxin can enter the body through wounds, cuts, or burns, highlighting the importance of proper wound care and hygiene.

**Correct Answer:** C.