Final answer:
The two significant ways that neurons change during the first years of life are through rapid myelination and increased connectivity among neurons. These processes contribute to the development of the nervous system and cognitive functions in early childhood. The correct option A.
Step-by-step explanation:
During the first years of life, the two significant ways that neurons change are through myelination and the increase in connectivity among neurons. Myelination is the process where myelin sheaths form around the axons of neurons, which greatly speeds up the conduction of nerve impulses. This process contributes to the efficiency and functionality of the nervous system. As children grow, connectivity among neurons also increases through the growth of new synaptic connections, a key component of neuroplasticity. This enhanced connectivity is crucial for cognitive development and learning.
While it was once believed that the brain cells we are born with are all that we will have, more recent research acknowledges that neurogenesis can take place in some brain regions, although this is a much more limited process compared to the proliferation of synapses that happens during early childhood. Furthermore, neurons are highly specialized, and different types of neurons have distinct sizes and shapes that relate to their unique functions. However, the bulk of neural development in terms of quantity and complexity of connections occurs predominantly during early developmental stages, making myelination and connectivity the primary factors in neural change during these years.