Re: In terms of physics, the characteristic feature of the

(A) cars potential energy, gained through their being lifted by a chain drive (their -- ??, doesnt looks right)
(B) cars potential energy, a gain achieved as they are lifted by a chain drive (a gain is the characteristic of roller coaster?? - meaning issue)
(C) potential energy from the cars being lifted by a chain drive (being is generally avoided)
(D) potential energy of the cars, gained as a chain drive lifts them -- this seems okay
(E) potential energy gained by the cars, being achieved while a chain drive lifts them (same as C)

A tricky one indeed