Reflex arc is a way of exciting conduction.

A, the transmission of excitement in the reflex arc is unidirectional, and the direction is e→d→c→b→a, A error;

B and D are located between ganglion and receptor, which are dendrites of neurons. B is wrong.

C, the transmission of excitement in the reflex arc is one-way, stimulating point B, not measuring action potential at point E, C error;

D, the transmission of excitement in the reflex arc is one-way, the direction is e→d→c→b→a, and D is correct.

Therefore, choose: d.