Task: Question Answering
Input (English): Question: A potential receiver: 
 Options:  <1> It is produced by the opening of voltage-dependent channels. <2> Increase its frequency if the intensity of the stimulus increases. <3> It occurs after the binding of the neurotransmitter to the postsynaptic receptor. <4> They occur if the trigger threshold is exceeded. <5> It can be exciter or inhibitor.
Output (English): 5