Which of the following describes a standing wave? a. identical waves, same direction same medium c. identical waves opposite direction, same medium b. nonidentical waves, opposite direction different medium d. nonidentical waves, same direction, different medium

In physics terms, a standing wave is commonly defined as a wave formed by the interference of waves comprising identical frequencies. In addition, it also has is nodes wherein the wave is at its minimum amplitude. Therefore, the answer would be " identical waves, same direction same medium."