One of the major changes in brain development between the ages of 3 and 15 involves an increase in the speed and efficiency of information traveling through the nervous system. This change is brought about by .

Myelination

Explanation:

Myelination is the process of the formation of the myelin sheath around the neurons. The myelin sheath is composed of the fats and few proteins and since fat is present in the high amount therefore the myelin sheath provides insulation to the neuron.

The myelin sheath increases the speed and efficiency of the electrical impulse transmission in the neurons.  In the given question, the changes in the neurons taking place during the development process is due to the myelination process which increase efficiency.

Thus, myelination is correct.

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