Answer:
A) Absorption into the myelin sheath
Step-by-step explanation:
The myelin sheath is an insulating layer that surrounds the axons of some neurons. It helps to speed up the transmission of nerve signals. Neurotransmitters are released from the axon terminal and bind to receptors on the postsynaptic neuron. Once the neurotransmitter has bound to the receptor, it is removed from the synapse by diffusion, reuptake into the presynaptic neuron or astrocytes, or breakdown by enzymes.
The other options are all means whereby neurotransmitters are removed from the synapse:
O B) Breakdown by enzymes in the postsynaptic neuron. Some neurotransmitters are broken down by enzymes in the postsynaptic neuron after they have bound to receptors.
O C) Diffusion away from the synapse. Neurotransmitters can also diffuse away from the synapse, but this is a slow process.
O D) Re-uptake by presynaptic neuron or astrocytes. Many neurotransmitters are reabsorbed by the presynaptic neuron or by astrocytes. This is the most common way that neurotransmitters are removed from the synapse.