Could you supply u with some answer choices please?
The mechanical energy of the roller coaster is sum of kinetic energy K and gravitational potential energy U:

where

is the kinetic energy

is the gravitational potential energy
Since the ride is frictionless, the total mechanical energy E is conserved during the ride. Therefore, at the top of the hill, the potential energy is maximum, because h (the height) is maximum, and this means the kinetic energy is minimum (because the sum of K and U is constant), so the velocity will be minimum. Viceversa, at the bottom of the hill, the potential energy will be minimum (because h is minimum), so the kinetic energy K will be maximum, and the velocity v of the roller coaster will be maximum.
A. Discovering a quick way to handle a new problem
Terminal speed is the maximum speed that a falling object can reach and is based on aerodynamic resistance. In a vacuum, an object falling toward a planet as a result of gravity will continue to accelerate until it hits the ground.
However, if the object is falling through an atmosphere, such as on earth, then it will accelerate up to the point that the aerodynamic resistance cancels the downward force due to gravity, and it travels at a constant maximum speed, called the terminal velocity. At this point, resistance is equal to acceleration due to gravity. At terminal velocity, the skydiver's acceleration is zero.
The correct answer is option D, "The pigment chlorophyll reflects green light waves"
The chloroplast with in the plants consists of chlorophyll (green colour pigment) which is highly absorbent to the long and short wavelengths such as red and blue wavelength of visible spectrum and reflects green wavelengths thereby producing green colour visualizations to the viewer. The two common chlorophyll usually found in the leaves are chlorophyll A and B. Chlorophyll A is majorly responsible for reflecting the green light