[单选题]
An echo is heard 2.0 s from a cli367bo u5;m;jke )p lih p7jx:ztk ho.jt 7yaax14pwfkk 0)ud 8ff on a day the temperature is $15 \; ^{\circ}C$. Approximately how far is the cliff from the observer?
A. $85 \; m$
B. $170 \; m$
C. $340 \; m$
D. $680 \; m$
