Select the incorrect option for electrical synapses.

Identify the labelled parts $A, B$ and $C$ from the given diagram.

Parkinson's disease (characterized by tremors and progressive rigidity of limbs) is caused by degeneration of brain neurons that are involved in movement and control. Identify the neurotransmitter responsible for this.

The following figure shows the axon terminal and synapse. What is the function of $P$?

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.

Acetylcholine is: