Refer to the Figure Shown

Refer to the figure shown.
Which statement best describes what is occurring in the bottom panel?

A) More electrical stimulation is occurring on the voltage-gated channels; therefore, they open with more frequency.
B) The increased concentration of acetylcholine eventually overwhelms the receptors, and the bottom panel represents what will happen just before they remain open permanently.
C) Because the channels are staying open longer due to increased acetylcholine concentration, K⁺ begins to move in significant quantities.
D) In this section of membrane, there are two acetylcholine channels that, in the presence of increasing neurotransmitter concentration, have an increasing probability of being open at the same time.