Refer to the Figure Showing an Experiment in Which One

Refer to the figure showing an experiment in which one neuron is being measured under two conditions.
Which statement best explains why this neuron is not especially active in condition 2?

A) The M1 motor neuron being measured is specifically involved in picking up a box, but the subject realizes there is no box in condition B, so the motor neuron fires less robustly.
B) The mirror neuron being measured is specific to reaching for a box, and there is no box in condition B.
C) The mirror neuron being measured is from an autistic subject, thus this copycat neuron is underactive
D) The SMA neuron being measured is active in condition A, when the subject is reaching for a box, but not in condition B, when the subject is simply mentally rehearsing the complex movement sequence.