In the process of beginning an action potential, the threshold refers to:
neuron extensions that conduct messages toward the cell body. a minimum intensity of excitatory minus inhibitory stimulation. neuron extensions that send messages to other neurons. the junction between a sending and receiving neuron.

Option (3).

Explanation:

The action potential may be defined as the change in the electric potential of the cell that helps in the propagation of the nerve impulse. The resting membrane potential of the cell is -70mV.

Threshold potential may be defined as the minimum potential required to transmit the nerve impulse. If the difference between the excitatory signal and inhibitory signal exceeds the minimum intensity, known as threshold. The propagation of nerve impulse occurs.

Thus, the correct answer is option (3).

not sure if this what   you'r looking for would be percent composition