A highway curve of radius 80 m is banked at 45°. Suppose that an ice storm hits, and the curve is effectively frictionless. What is the speed with which to take the curve without tending to slide either up or down the surface of the road?

A) 9.4 m/s
B) 28 m/s
C) 78 m/s
D) The curve cannot be taken safely at any speed.