Which type of wave results in a lesser amplitude wave?

The phenomenon of wave interference plays a crucial role in understanding how waves interact, particularly in relation to amplitude. When two waves are out of phase, they can interfere destructively. This means that when a crest of one wave aligns with a trough of another wave, their amplitudes can subtract from one another.

In the case of an out-of-phase wave interaction, if the waves are perfectly out of phase (180 degrees apart), the resultant amplitude can be minimized dramatically, potentially leading to complete cancellation. Therefore, when two waves that are out of phase combine, the amplitude of the resulting wave is indeed less than that of the individual waves, which is the key concept behind this option.

In contrast, in-phase waves reinforce each other; thus, they combine to create a larger amplitude wave. Standing waves and longitudinal waves are types of waveforms that do not inherently cause a reduction in amplitude through the process described in this question. Hence, the out-of-phase wave is the only option that distinctly leads to a lesser amplitude result due to the destructive interference that occurs when these waves interact.