Question

c =
axon terminal/synaptic knob
dendrite
axon
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cell body

Explanation:

In a neuron structure, the labeled part (c) is the long, insulated fiber that carries electrical signals away from the cell body, which is defined as the axon. The cell body is (b), axon terminals are (d), and dendrites are the branching structures extending from the cell body.

Answer:

Axon