The right answer is A. intersections ... another neuron.
The synapse refers to a functional contact zone that is established between two neurons, or between a neuron and another cell (muscle cells, sensory receptors ...). It ensures the conduction of an action potential in the presynaptic neuron into a signal in the postsynaptic cell. It is estimated that for some cell types (eg pyramidal cell, Purkinje cell ...), about 40% of the membrane surface is covered by synapses.
