Which of the following statements is true regarding standing waves?

Standing waves are characterized by their formation of fixed points known as nodes and antinodes, making the statement that they have these features true. Nodes are points along the medium where there is minimal or no displacement of particles, while antinodes are points where maximum displacement occurs. This structure arises due to the interference of two waves traveling in opposite directions, typically in a medium.

The other statements do not accurately describe standing waves. For instance, standing waves can exist in various media—such as strings, air columns, or water—rather than being restricted to a vacuum. They are also not exclusively linked to sound; they can involve other types of waves, including electromagnetic and mechanical waves. Lastly, standing waves require a medium for their formation, as they rely on the waves interacting within that medium to create the nodes and antinodes. Thus, the key characteristic of having nodes and antinodes solidifies the truth of the correct statement regarding standing waves.