A given signal’s second harmonic is twice the given signal’s __________ frequency?

The correct answer is C. Fundamental.

A harmonic is a frequency that is an integer multiple of the fundamental frequency. The fundamental frequency is the lowest frequency in a complex waveform. The second harmonic is twice the fundamental frequency, the third harmonic is three times the fundamental frequency, and so on.

In the case of a given signal, the second harmonic is twice the given signal’s fundamental frequency. This is because the second harmonic is a frequency that is an integer multiple of the fundamental frequency, and the fundamental frequency is the lowest frequency in the complex waveform.

The other options are incorrect.

• Option A, Fourier, is incorrect because it is not a frequency. The Fourier transform is a mathematical tool that can be used to decompose a complex waveform into its constituent frequencies.
• Option B, Foundation, is incorrect because it is not a frequency. The foundation of a building is the part that supports the weight of the building.
• Option D, Field, is incorrect because it is not a frequency. A field is a region of space in which a physical quantity, such as a force or a magnetic field, has a value at every point.