Correct Answer:
C. Television
A television is unequivocally an audio-visual teaching aid, making it the correct answer. Audio-visual aids are tools that engage both the sense of hearing (audio) and sight (visual) simultaneously, enhancing comprehension and retention. A television achieves this by presenting both sound and moving images, which is highly effective for conveying complex information, demonstrating processes, or bringing dynamic real-world scenarios directly into the learning environment. In contrast, a chalkboard is primarily a visual aid, a radio is exclusively an audio aid, and a textbook is predominantly a visual (text-based) aid. The dual sensory input of television provides a more comprehensive and engaging learning experience.