What Are the Similarities Between Sodium, Potassium, and Calcium Ion

Multiple Choice

What are the similarities between sodium, potassium, and calcium ion channels?

A) All allow passage of multiple different ions.
B) They contain homologous domains in the membrane spanning regions.
C) They all contain voltage-sensing segments that close the channel in response to a particular membrane potential.
D) They are capable of moving ions in both directions across a membrane.
E) None of the answers is correct.