The diagram below shows stream gradient. If a stream has a horizontal distance of 20 km and begins at an elevation 100 m higher than where it ends, what is its stream gradient?
		A.	20 km + 100 m = 120 km/m
 		B.	100 m / 20 km = 5 m/km
 		C.	100 m × 20 km = 2000 m/km
 		D.	20 km / 100 m = 0.20 km/m
                                             
                                          
                                          
                                        
											 
					                  