Final answer:
The sodium-potassium pump transports sodium out of the neuron and potassium into it, which is essential for maintaining the neuron's resting membrane potential and is critical for nerve impulse transmission.
Step-by-step explanation:
At the normal resting potential of a typical neuron, its ion exchange pump, known as the sodium-potassium pump, actively transports ions across its membrane to maintain a specific electrical gradient. This pump uses energy to move sodium (Na+) out of the neuron and potassium (K+) into the neuron. Specifically, the pump moves three sodium ions out for every two potassium ions it moves in, utilizing energy from ATP. This activity is what generates the neuron's resting membrane potential, making the inside of the neuron negatively charged relative to the outside environment.
The correct answer to the question is: a) Sodium out and potassium in. This action contributes to the difference in charge across the cell's membrane, which is essential for the transmission of nerve impulses. By establishing a net negative charge inside the cell, the sodium-potassium pump plays a critical role in neuronal function.