Answer:
a. Cardiac muscle can't be tetanized is the correct answer.
Explanation:
Cardiac muscles are present in the heart region and its function is to perform involuntary muscular motions.
Skeletal muscle is also called a voluntary muscle and skeletal muscles are attached to the bones and its function is to provide protection to the internal organs and movements of bones.
The shape of the cardiac muscle is semi spindle and it is shorter in length whereas the shape of the skeletal muscle is cylindrical and it is longer in length.