[单选题]
A horizontal curve on h.*5awp)f udhfw(3 a;a6bg goa bobsled run is bank nyg1l(m2 ow-a7k5kgm; a/nuwed at a $45^{\circ}$ angle. When a bobsled rounds this curve at the curve's safe speed (no friction needed to stay on the run), what is its centripetal acceleration?
A. $1.0 \; g$
B. $2.0 \; g$
C. $0.5 \; g$
D. none of the above
