Question

what is the name of the structures labeled \b\?
synaptic vesicles
myelin sheaths
muscle fibers
motor neurons

Explanation:

Synaptic vesicles are small sacs in neurons that store neurotransmitters. Myelin sheaths are insulating layers around nerve fibers. Muscle fibers are the cells that make up muscles. Motor neurons transmit signals from the brain or spinal - cord to muscles. Based on the context of the image which seems to be related to a neural - muscular connection, the structures labeled B appear to be muscle fibers.

Answer:

Muscle fibers