Some engineers have suggested that we can simulate gravity in outer space by having a circular rotating space station where persons feel an outward – directed fictitious force due to the rotation of the station. the reason they feel such a force is because

Centrifugal force

Explanation:

In Space, It is in a way possible create an " artificial gravity" just by spinning the aircraft or space station. On spinning the space station the inhabitants feel an outward force or the centrifugal force, this outward force when equivalent to gravitational force is able to stimulate gravity.

at positions a, g kinetic energy is maximum.

at position d, potential energy is maximum.

i think the answer is a, hope this : )