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

marginal cost is a microeconomic measure that us to evaluate the extent to which the level of production of a good is sustainable in accounting, that is, to how many quantities the company plans to profit from the production of the good.

the concept of marginal cost is simple, it means the cost of producing one more item. for example, in the case of pies, the marginal cost is the cost of producing one more pie than those that have already been produced.

it is important to understand that productive activity influences marginal cost. the marginal cost of some goods can be very high, while others may be insignificant. for example, the marginal cost of producing an extra plane is very high. already the marginal cost of a water company to provide 1l more water is derisory.

in the case of pies, the cost involves the inputs, the labor and the fixed cost, which involves the fixed space of the bakery. the level of production initially has the marginal cost decreasing because there is space and manpower available. however, to produce more you have to hire more workers and buy more inputs. if physical space is limited, workers will conflict with places, inputs and their productivity will decrease, meaning there is an optimum point of production for each level of space and manpower. from this point on, the productivity of the workers will be getting smaller because of lack of space, so that the marginal cost of producing one more pie will be increasing. so, although you have not posted the chart, but if you have the answer, you can see that my explanation goes according to the marginal cost curve that will increase from the 4th pie, answer (c).