[单选题]
If you walk 6.0 km in zqzjr ;(;v *ap 3p8gfha straight line in a directiohj you*0l l m msm 5u(2fl0k5;.i7nqswn north of east and you end up 2.0 km north and several kiqll0iys w*u h2m0 5 nu.7kfm5; smjo(llometers east. How many degrees north of east have you walked?
A. $19^{\circ}$
B. $45^{\circ}$
C. $60^{\circ}$
D. $71^{\circ}$
