Which of the following create harmonics?

### Nonlinear behavior

## Step1: Understanding Harmonics### Harmonics are multiples of a fundamental frequency. They occur due to the superposition of waves, where the wave pattern repeats itself at regular intervals.## Step2: Identifying the Source of Harmonics### Harmonics are created when a wave or signal interacts with another wave or signal that has a frequency that is an integer multiple of the fundamental frequency. This interaction can be due to various physical phenomena.## Step3: Recognizing Nonlinear Behavior### Nonlinear behavior in physical systems, such as sound or light, can cause the creation of harmonics. This is because nonlinear behavior allows for the constructive interference of waves at frequencies that are integer multiples of the fundamental frequency.