The correct option is A Both the assertion and reason are true and the reason is the correct explanation for the assertion
A nerve impulse is transmitted from one neuron to another through junctions called synapses. A synapse is formed by the membranes of a pre-synaptic neuron and a post-synaptic neuron, which are separated by a gap called synaptic cleft.
There are two types of synapses, namely, electrical synapses and chemical synapses. In electrical synapses, the synaptic cleft is only 0.2 nm and in chemical synapses, the synaptic cleft is 10-20 nm wide. Hence impulse transmission across an electrical synapse is always faster than that across a chemical synapse.