Final answer:
The brain consists of approximately 100 billion nerve cells called neurons, which are central to transmitting nerve impulses throughout the nervous system.
Step-by-step explanation:
The Brain's Nerve Cells
The brain is an incredibly complex organ consisting of approximately 100 billion nerve cells known as neurons. These neurons are responsible for transmitting nerve impulses throughout the nervous system, making them central to all brain and body functions. Neurons have a specialized structure that includes a cell body with dendrites and an axon to facilitate this transmission of electrical signals. Unlike protons and electrons, which are particles within atoms, neurons are living cells that form the critical infrastructure of our nervous system. Additionally, neurons are supported by glial cells, which provide essential support functions but do not carry nerve impulses themselves.
In summary, the correct answer to the student's question is (a) neurons.