A Roller Coaster Starts from Rest at the Top of an 18-M

A roller coaster starts from rest at the top of an 18-m hill as shown.The car travels to the bottom of the hill and continues up the next hill that is 10.0 m high. How fast is the car moving at the top of the 10.0-m hill, if friction is ignored?

A) 6.4 m/s
B) 8.1 m/s
C) 13 m/s
D) 18 m/s
E) 27 m/s