Correct Answer - Option 4 : Graphs
Teaching-learning materials (TLMs) also known as instructional aids, facilitate a teacher in achieving the learning objectives formulated by her/him prior to teaching-learning activities start.
One of the ways of categorization of TLMs is based on the audio and visual effects produced by the materials.
Accordingly, there are three types of TLMs:
Audio Aids: The materials or devices which call upon the auditory senses and thus help the individuals to learn through listening e.g. Radio broadcasts, Cassette and CD player.
Visual Aids: The aids which call upon the visual senses and thus help the learners to learn through viewing. The important and under this head are Blackboard, Charts, Pictures, Graphs, Models, Film strips, Slides, Puppet, Flashcards, Games etc.
Audio-Visual Aids: The devices which require the auditory as well as visual senses and helping the students to learn through listening as well as viewing. Examples of such aids are television, films and computer-assisted instruction.
Hence, we can say that graph is not an audio-visual aid, but a visual aid.