In which scenario is an animal doing work? Choose three correct answers.

Work occurs when a force causes an object to move in the direction of that force. The horse pulls the wagon forward, the bird lifts the worm upward against gravity, and the cat lifts her kitten, so each does work. The goat pushing against a wall that does not move does no work on the wall, and rubbing against a tree does not involve moving the tree in the direction of the applied force.

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