Final answer:
The parts of brain development responsible for improvements in memory, attention, and processing speed are myelination and pruning, synaptogenesis, and neurogenesis.
Step-by-step explanation:
The part(s) of brain development responsible for improvements in memory, attention, and processing speed are myelination and pruning, synaptogenesis, and neurogenesis.
Myelination and pruning involve the formation of myelin sheath around axons, which allows for faster and more efficient communication between neurons. Synaptogenesis refers to the formation of new synapses, which enhances the connection between neurons and improves memory and attention. Neurogenesis is the generation of new neurons, which contributes to the development and functioning of the brain.