Answer:
B. Tetany
Explanation:
Tetany refers to the involuntary sustained contraction of the muscles and causes severe twitch. The refractory period of the cardiac muscles refers to the time interval during which a second contraction in the muscles can not be triggered.
The cardiac muscles have a longer refractory period than skeletal muscles. This ensures that the next contraction can not start unless the cardiac muscle has relaxed properly.
The refractory period longer than the contraction itself ensures that the cardiac muscles do not exhibit the sustained muscle contraction, that is, they do not exhibit tetany.