Which of the Following Does NOT Correctly Describe Cardiac Muscle Cells

Multiple Choice

Which of the following does NOT correctly describe cardiac muscle cells?

A) They are arranged in layers surrounding hollow cavities in the heart.
B) They are much shorter than skeletal muscle fibers,and generally have a single nucleus.
C) Their membranes are depolarized initially by the influx of sodium ions.
D) They depolarize prior to contraction.
E) They can contract in the absence of external calcium.