A Thunderstorm Is Brewing in the Distance $340 \mathrm {~m} / \mathrm { s }$

A thunderstorm is brewing in the distance. Upon seeing a flash of lightning you begin counting the seconds until you hear the thunder and notice that it took 5 seconds for the sound of
Thunder to reach you. Assuming the speed of sound in air to be $340 \mathrm {~m} / \mathrm { s }$ , how far away was the
Lightning strike?

A) 1.7 km
B) 2 km
C) 5 km
D) 10 km