An action potential can start in the middle of an axon and ...

[geoffrey]

An action potential can start in the middle of an axon and proceed in both opposite directions when
A) the neuron is an inhibitory neuron and operating normally.
B) only the middle section of the axon has been artificially stimulated by an electrode.
C) the dendritic region fires an action potential.
D) it is in its typical refractory state.
E) its membrane potential is above the threshold.

[j_sun]

I recall doing this last year, it's B, bye bye!