The correct answer is option d, that is, neurotransmitters.
A neurotransmitter refers to a chemical component, which is discharged at the terminal of a nerve fiber by the introduction of a nerve impulse, and by diffusing across the junction or synapse. It helps in the transfer of the impulse to another muscle fiber, nerve fiber, or some other composition. Acetylcholine is a kind of neurotransmitter, that is, used by neurons in the CNS and the PNS in the control of activities ranging from heart rate and muscle contraction to digestion and memory.
Answer:
The Easter Island once used to be extremely diverse in biodiversity. It had abundant amount of plant and animal species living there.
Biodiversity in the past was extremely high due to favorable conditions there. The temperature and climate of Island was favorable for the growth of plants and animals.
It has mild climate with fertile soil which favored growth but now the scenario is different as it is now barren land with lots of sand and no diversity among plants and animal species is found there.