[单选题]
Your motorboat can m kv .h9r/xjoleyov8 0 +y:)aqvove at 30 km/h in stilxm6fr+hcgtzcib2d xl 1 .*0im,g6hu)l water. How much time will it take you to move 12 km downstream, in a rivi h,l riu1b+6. gxmm 2)*zchf6g0dtxcer flowing at 6.0 km/h?
A. $20 \; min$
B. $22 \; min$
C. $24 \; min$
D. $30 \; min$
