Tetanus germs produce a toxin. It affects

The correct option is voluntary muscles.

Tetanus is a serious nervous system disease caused by the bacterium Clostridium tetani. When these bacteria enter the body, they produce a highly potent neurotoxin called tetanospasmin. This toxin specifically targets the nerve cells that control muscle movement.
Under normal conditions, inhibitory neurotransmitters (such as GABA and glycine) act as a brake to prevent motor neurons from over-firing. Tetanospasmin blocks the release of these inhibitory transmitters, causing the motor nerves to continuously send signals to the muscles to contract.

Because there is no signal to relax, the affected muscles experience sustained, painful, and uncontrolled contractions (spasms). This spasm activity is highly characteristic of skeletal muscles, which are voluntary muscles under our conscious control (such as the muscles in the face, neck, and limbs).
A classic sign of tetanus is "lockjaw" (trismus), which is the painful contraction of the masseter muscle (a voluntary muscle used for chewing). The toxin does not affect the jaw bones directly, nor does it primary target involuntary muscles (like cardiac muscle or smooth muscle in organs).