Answer
C
Work Step by Step
Applying the Pythagorean Theorem:
$$ 6400^2+d^2=\left(6400+2.5\right)^2 \\ 40960000+d^2=40992006.25 \\ d^2=32006.25 \\ d=179 km$$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.