Two waves with similar frequencies are added. The traces show the resulting waveforms that occur when two different pairs of waves are added. Graph is for the same time interval in both cases, which of the following statements is TRUE?
 
 

On average, the waves on the right had higher frequencies, but the difference between frequencies less

On average, the waves on the left had higher frequencies, but the difference between frequencies less

On average, the waves on the right had higher frequencies, but the difference between frequencies more

On average, the waves on the left had higher frequencies, but the difference between frequencies more