Final answer:
An oscillation is a back and forth motion of an object between two points of deformation. It occurs when there is a restoring force on an object, which can result from a one-dimensional force or a spring.
Step-by-step explanation:
An oscillation is a back and forth motion of an object between two points of deformation. It occurs when there is a restoring force on an object. A restoring force can arise from a one-dimensional force applied to an object, like a pendulum swinging due to gravity, or from a spring, like a mass-spring oscillator. Therefore, the correct answer is D) both A & B.