Concept:Effective teaching methods for language acquisition.Explanation:When teaching a language, especially to young learners or in a new language context, using non-verbal cues like gestures, facial expressions, and physical actions can significantly help in conveying meaning.These methods are particularly useful for introducing new words and their meanings because they provide a visual and kinesthetic link to the concept.For instance, smiling and nodding can teach "happy," or pretending to wear a hat can teach the word "hat."This approach aids understanding and retention by engaging multiple senses and making abstract words more concrete.Therefore, gestures, expressions, and actions are a key technique for teaching Vocabulary.Answer:C. Vocabulary