Which term refers to an early system of paving roads with crushed rock and asphalt?

A. concrete

B. cobblestone

C. corduroy

D. macadam

The correct answer is D) macadam. Macadam was an invention keyed by a Scottish man who changed the way we view paving of roads and highways. Macadam is a mixture of small stones crushed together with asphalt, the sticky, black material used for both concrete and macadam. The name Macadam comes from the engineer's name, which was John Loudon McAdam. There had been other attempts at macadam before McAdam, but McAdam improved it and his was the first to arrive in the United States.

The answer is D. Macadam