Which agent or condition is not correctly paired with its effect on muscle contraction?

I found the full exercise on the internet. Bellow are the options.
"A. tetanus toxin / muscle stays contracted
B. botulinum toxin / muscle stays relaxed
C. black widow spider venom / muscle stays contracted
D. acetylcholinesterase inhibitor / muscle stays relaxed
E. curare / muscle stays relaxed"

The option that's not correct is the option D. The acetylcholinesterase inhibitor is responsible by muscle contraction. This inhibitor will have its effect in the neuromuscular junction inhibiting the acetylcholinesterase to break down acetylcholine allowing it to have its effects for longer, being one of them to activate muscles. It used for example to treat myasthenia gravis, which is a weakening of the muscles.

Genetic engineering is the answer.

The answer is constant.