Biology · Coordination and Control

Neurotransmitters: Correct, as neurotransmitters are the chemical messengers that transmit signals across the synapse between neurons.

Synaptic knob of synapse: Incorrect, as this refers to the part of the neuron that releases neurotransmitters, not the chemical messengers themselves.

Reflex actions: Incorrect, as reflex actions are automatic responses to stimuli, not chemicals that transmit signals across synapses.

Neurotransmitters: Correct, as neurotransmitters are the chemical messengers that transmit signals across the synapse between neurons.

Acetylcholinesterase: Incorrect, as acetylcholinesterase is an enzyme that breaks down acetylcholine, a type of neurotransmitter, rather than being the neurotransmitter itself.