Tetanus (or lockjaw) is a serious infection caused by Clostridium tetani bacteria which produce a toxin that affects the brain and nervous system. The toxin leads to stiffness in the jaw muscles as well as other muscles. The infection can cause severe muscle spasms, serious breathing difficulties, and can ultimately be fatal. Clostridium tetani spores can be found most commonly in soil, dust and manure. When they enter a deep wound, spores of the bacteria may produce a powerful neurotoxin, tetanospasmin, which actively impairs motor neurons (nerves that control muscle movement).
Therefore, the correct answer is option C.