What Speed Should a Roller Coaster Have at a Point

Multiple Choice

What speed should a roller coaster have at a point 30 m above the bottom of a dip if it is to barely reach the top of the next slope, which is 40 m above the bottom of the dip? Neglect friction.

A) 0 m/s
B) 14 m/s
C) 28 m/s
D) 98 m/s
E) 2.0* 10² m/s