Some evidence that the nervous and endocrine systems are evolutionarily ... ...

Some evidence that the nervous and endocrine systems are evolutionarily related comes from the fact that certain molecules function similarly to hormones during transmission of nerve impulses. Which of the following types of molecules fits this description?
(A) The sodium potassium pump
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in 14. The Nervous and Endocrine Systems