Which one of the following statements is correct in respect of the theory of stability?

A. Phase margin is the phase angle lagging, in short of 180°, at the frequency corresponding to a gain of 10

B. Gain margin is the value by which the gain falls short of unity, at a frequency corresponding to 90° phase lag

C. Routh's-Hurwitz criterion can determine the degree of stability.

D. Gain margin and phase margin are the measure of the degree of stability

Answer: Option D