Final answer:
When two waves superimpose during superposition, it's the amplitudes of the waves that get added together, resulting in a wave that represents the simple addition of the individual wave amplitudes.
Step-by-step explanation:
When two waves superimpose, their disturbances, which correspond to forces, are added together. This phenomenon is known as superposition. Specifically, when two disturbances meet along the same line, their amplitudes are added to produce the resulting wave.
An important aspect of superposition is that it does not combine other properties of the waves, such as frequencies, phases, or velocities. Therefore, when determining what gets added together during superposition, the correct option is that their amplitudes are added.