Answer the following question: You are presented with the quiz "What do animals require to move?"   But you don't know the answer, so you turn to your teacher to ask for hints. He says that "an animal requires energy to move" and "animals get their energy from food".   So, what's the best answer to the question?

Choose your answer from:
 * Heat.
 * Prey.
 * warmth.
 * oxygen.
 * Shelter.
 * air.
 * Food.
 * Predators.
Answer:
Food