A surprising aspect of brain growth is that
a. the neural tube produces far fewer neurons than the brain will need. b. as synapses form, 20 to 80 percent of the surrounding neurons die. c. during infancy and toddlerhood, neural fibers stagnate.
d. once neurons are in place, they cannot differentiate.

The correct option is B: as synapses form, 20-80% of the surrounding neurons die

Explanation:

One very surprising aspect of growth of brain is how cells are programmed to die, and thus creates space for connective structures. Thus, the formulation of synapses is accompanied by the death of 20 to 80 percent of neurons, although this is dependent on the region of the brain. It is however fortunate that the prenatal period is accompanied by the production of more neurons by the neural tube capable of always satisfying the needs of the brain.