To estimate the distance of 5,686 miles in the form of a single digit number times a power of 10, we first look for a single digit number that is closest to 5,686.
The number 5,686 is closer to 6,000 than to 5,000, and we can express 6,000 as:
\[ 6,000 = 6 \times 10^3 \]
Since \( 5,686 \) is approximately \( 6 \times 10^3 \), the best estimation from the options provided is:
6×10^3 (6 times 10 to the 3rd power).