Chemical signal released by nerve cells is:
(a) ligand
(b) neurotransmitter
(c) proteins
(d) glycogen

The correct answer will be option-B.

Explanation:

A neurotransmitter is a chemical messenger used by the nerve cells to transmit the signals from one neuron to another neuron and muscle cell at the synaptic cleft. The common neurotransmitter is acetylcholine, dopamine, serotonin and others.

The neurotransmitter can be excitatory that is causing the generation of the action potential in the neurons or inhibitory that is prevent the generation of neuron in neuron cell. This depends on the receptors to it binds.

The neurotransmitters can be degraded or can be taken back after the work is completed. thus, Option-B is the correct answer.

spiders belong to a group of arachnids.

arachnids have the following traits :

they have two body parts.

they have eight legs unlike insects which have 6 legs.

they have no wings.

these traits distinguish them from insects.

the information that antonio is doubting us the statement that spiders differences are as a result of being first to evolve.

this is because the evolution of one species is independent of the other species.