Which structure of the nervous system carries action potential in the direction of a synapse?

The correct answer is B: axon. The axon is a long, slender projection of a neuron that conducts electrical impulses away from the neuron's cell body towards other neurons or target cells, such as muscles or glands, including towards a synapse. The cell body contains the nucleus and other organelles but does not carry action potentials. While a neuron is the overall structural and functional unit of the nervous system, the axon is specifically responsible for transmitting action potentials.