Parkinson's disease (characterized by tremors and rigidity in limbs) is caused by the degeneration of neurons in the brain that are associated with the secretion and use of which neurotransmitter?

Which of the following statements are correct regarding electrical synapses?
$i.$ At electrical synapses,the membranes of pre- and post-synaptic neurons are in very close proximity.
$ii.$ Electrical current can flow directly from one neuron into the other across these synapses.
$iii.$ Impulse transmission across an electrical synapse is very similar to impulse conduction along a single axon.
$iv.$ Electrical synapses transmit signals using neurotransmitters like acetylcholine.
$v.$ Electrical synapse transmission is very fast.
$vi.$ Electrical synapses are rare in our system.

Assertion $(A) :-$ Impulse transmission across an electrical synapse is always faster than that across a chemical synapse.
Reason $(R) :-$ Electrical current can flow directly from one neuron into the other across electrical synapses.

In the parasympathetic nervous system,which of the following is released?

Assertion : The chemical stored in the synaptic vesicles are termed as neurotransmitters.
Reason : Synaptic vesicles release these chemicals in the synaptic cleft.

Which part of the neuron is responsible for the release of neurotransmitters?