Here's a problem to solve: An engineer is analyzing which areas in a city might become flooded if there are heavy rains. Which of the following maps is best to use for this analysis?

Among the 4 following options, which is the correct answer?

- A: a map showing the routes of city buses
 
- B: a map showing the locations of streets
 
- C: a map showing the locations of houses
 
- D: a map showing the elevations of ground surfaces
 