The future of cities in the United States and in other countries will be determined by their ability to benefit from the and to minimize or counterbalance the .

The correct answer is letter "B": Economies of agglomeration; corresponding diseconomies.

Explanation:

Economies of agglomeration refer to a type of economy in which companies are located one close to another to take advantage of their core competencies. This economic structure typically helps businesses to reduce relocation and delivery costs increasing their profits but in some other cases, the costs could increase if some of the firms lost their economies of scale.

Thus, metropolises in the U.S. must find ways to boost the benefit of economies of agglomeration minimizing the negative effects of the diseconomies of scale in which some firms might fall.