Question

practice it
what are neurotransmitters?
proteins that transport oxygen in the blood
hormones that regulate the bodys metabolism.
ions that regulate the ph in the body
chemical messengers that bind to receptors on the next neuron, transmitting the signal across the synapse.
antibodies that fight off infections

Explanation:

Neurotransmitters are chemicals released by neurons. They cross the synaptic - cleft and bind to receptors on the next neuron to transmit nerve signals. Proteins transporting oxygen are hemoglobin, hormones regulating metabolism include thyroid hormones, ions regulating pH are like bicarbonate ions, and antibodies fight infections.

Answer:

D. Chemical messengers that bind to receptors on the next neuron, transmitting the signal across the synapse.