Which of the Following Statements Concerning Action Potentials in the Heart

Multiple Choice

Which of the following statements concerning action potentials in the heart is correct?

A) The rising phase of the action potential in cardiac autorhythmic cells is due to a rapid Ca²⁺ influx.
B) The rising phase of the action potential in cardiac contractile cells is due to a rapid Na⁺ influx.
C) The plateau phase of the action potential in cardiac contractile cells is due to a slow Ca²⁺ influx.
D) Two of these answers are correct.
E) All of these answers are correct.