What is the largest part of a neuron that controls its metabolism and maintenance?

The soma, or cell body, of a neuron is indeed the largest part and plays a crucial role in the overall functioning of the neuron. It contains the nucleus, which houses the cell's genetic material, and is responsible for synthesizing proteins and other molecules necessary for the maintenance and metabolism of the neuron. The soma integrates incoming signals from the dendrites and is essential for the neuron's life-supporting functions, including energy production and the repair of cellular components.

In contrast, the axon primarily functions in transmitting electrical impulses away from the soma to other neurons, muscles, or glands, while the dendrites are responsible for receiving signals from other neurons. The terminal, or axon terminal, is where neurotransmitters are released to communicate with neighboring neurons but does not play a role in the intracellular metabolism and overall maintenance of the neuron. Therefore, the soma is correctly identified as the largest part of the neuron that is integral to its metabolic and maintenance functions.