Explanation :
The amplitude of the wave illustrates the energy of the wave. The energy of the depends on the amplitude and the frequency of the wave.
The maximum distance covered by the wave is called its amplitude. The topmost point on the wave is called its crest and the down most point is called its trough (as shown in the attached figure).
From the given data, the wave having the amplitude of 3 cm has the least energy while the wave having an amplitude of 12 cm have maximum energy.
So, the correct order of the wave from the lowest energy to the highest energy is :
1 < 4 < 2 < 3
Hence, this is the required solution.