Choose the best answer. Explain why it is the best answer. We care about the reasoning more than just having the right answer.

2. High population densities in central cities primarily reflect . . .

A. The poor live near the center and demography tells us that the poor have more children.

B. Land rents are high near the center, so apartments are smaller and buildings taller, both contributing to high density of population.

C. Zoning, which only allows high rises in central city neighborhoods.

D. None of the above.