In Which of the Following Ways Does Cardiac Muscle Differ

In which of the following ways does cardiac muscle differ from skeletal muscle?

A) Cardiac muscle is striated and skeletal muscle is not.
B) Cardiac muscle surrounds hollow tubes; skeletal muscle attaches to skin.
C) Cardiac muscle cells are electrically connected; skeletal muscle cells are not.
D) Cardiac muscle is under voluntary control; skeletal muscle is under involuntary control.
E) A group of cardiac muscle cells forms an organ; a group of skeletal muscle cells forms a tissue.