An airplane flight from Houston, Texas to Rome, Italy is 5,686 miles. Estimate the distance between the two cities as the product of a single digit number times a power of 10.
A: 6 X 10^4
B: 5 X 10^3
C: 6 X 10^3
D: 5 X 10^4
A: 6 X 10^4
B: 5 X 10^3
C: 6 X 10^3
D: 5 X 10^4