Kayla is 4 years old and has recently begun coordinating the two ...

[JGIBBSON]

Kayla is 4 years old and has recently begun coordinating the two sides of her body more efficiently. This development may be attributed to
 
  growth of the corpus collosum.
  longer arms and legs.
  brain lateralization.
  adequate calcium in her diet.

Question 2

The long band of nerve fibers that connects the brain's hemispheres is
 
  myelination.
  the corpus collosum.
  the prefrontal cortex.
  the axon cord.

[AmberC1996]

Answer to Question 1

growth of the corpus collosum

Answer to Question 2

the corpus collosum.