Consider the Action Potential Shown $\mathrm { Ca } ^ { + }$

Consider the action potential shown. Which of the following changes in membrane conductances for $\mathrm { Ca } ^ { + }$ and $\mathrm { K } ^ { + }$ best account for the prolonged plateau? (Assume normal colnductances for both ions during resting conditions, i.e., only the changes in conductances are important.)


A.

B.

C.

D.