1. To push your friend on a swing set as high as possible, (taking into account your safety as well) you: /5 (a) Push them from behind both as they are approaching you and as they are going away from you in their swing. (b) Push them only when they are approaching you, near the amplitude of their swing. (c) Push them only when they are moving away from you, near the amplitude of their swing. (d) Push them only when they are approaching you, near their equilibrium point. (e) Push them only when they are moving away from you, near their equilibrium point.