Which trail is the closest in length to 10.5 kilometers?

First of all you calculate the difference between the numbers:
10.5 - 10.653 = -0.153
10.5 - 10.592 = -0.092
10.5 - 10.732 = -0.232
10.5 - 10.484 = 0.016

You then select the difference with the smallest number (ignoring the positive and negative symbols). That happens to be the last one.

This means that the answer will be D) Spruce Trail.

Answers4.) -1/205.) -1/406.) -55/127.) -3/4