Light traveling through a piece of glass slows to 120.000 mi/s. What is the retractive index of this type of glass? (Speed of light (186282 Miles/second))

Which statement is true? a) the work done to lift an object 6 meters is greater than the gravitational potential energy it gains. b) the work required to push an object is less than the work required to pull an object the same distance. c) the work required to raise an object to a height is equal to the gravitational potential energy the object gains. d) the work done against gravity to lift an object straight up is greater than the work required to roll it up a ramp.