Why Are Urban Areas Susceptible to Flash Floods

Why are urban areas susceptible to flash floods?

A) Oil, gasoline, and other auto fluids repel more water into the stream system
B) City sewers promote flooding of city streets and parking areas
C) A high percentage of the surface area is covered with cement, asphalt, and other impervious materials
D) Construction materials promote rapid absorption of precipitation, which puts excess water into the stream system