In fourth grade, tate joins the school band and learns to play the trumpet. after a year of practice, the cortical regions in tate's brain responsible for motor coordination of the hands have increased dramatically. this phenomenon demonstrates that the brain has

 neural plasticity

Explanation:

               Neural plasticity is also known as neuroplasticity. It is the malleability of the brain to adapt itself to a change of regular practice and experience. It is the ability of our brain to change with changing environment as we develop and grow.

             In the context, Tate learns to play trumpet and after practicing for a year, Tate's brain has adapted to the instrument. He can play trumpet very well as his motor coordination to the brain increased dramatically. This is the result of the neuroplasticity of Tate's brain which have learned to adapt and change accordingly as he practiced for a year.

Therefore the answer is ---

 neural plasticity

answer; i do believe that the correct answer is (punch card ballots);

the answer is d.index