How Are Housing Starts, or New Construction, Used to Gauge

How are housing starts, or new construction, used to gauge the national economy?

A) Construction of apartments instead of single family homes indicates less money available in the economy.
B) Declines in housing starts are often one of the first signs of an approaching economic downturn.
C) Building supplies are the most profitable industry in the nation.
D) Decreases in demand for single-dwelling homes usually indicate a higher demand for condominiums and other multiunit construction.
E) Decreases in the average price of new homes indicate a strong economy.