Two cars are heading toward the same intersection. Car A travels due east at 20 miles per hour, and Car B travels due north at 50 miles per hour. At what rate, in miles per hour, is the distance between the two cars decreasing when Car A is 0.375 miles from the intersection and Car B is 0.5 miles from the intersection?
a)35 mph
b)46 mph
c)52 mph
d)70 mph