Concept: The sentence needs the correct past tense of the verb “lie” meaning “to recline.”Explanation:• “Lie” means to recline; its past tense is “lay.”• “Lay” means to put something down; its past tense is “laid.”• “Lain” needs a helping verb like “has” or “had.”• The lion is the subject doing the action, so the past tense form “lay” fits: The lion lay under the tree waiting for its prey.Answer: C. lay