In a control system, the bandwidth of a system roughly measures:

Correct option is D

​$$\begin{aligned}&\bullet \ \text{Bandwidth (BW) is defined as the frequency at which the magnitude of the closed} \\&\quad \text{loop system is equal to } 0.707. \\&\bullet \ \text{The bandwidth indicates the frequency range for which satisfactory operation occurs.} \\&\bullet \ \text{It roughly measures the gain crossover frequency.} \\&\bullet \ \text{Gain crossover frequency } (\omega_{gc}) \text{ is the frequency at which the gain magnitude of the} \\&\quad \text{closed loop system is equal to one.} \\&\bullet \ \text{Phase crossover frequency } (\omega_{pc}) \text{ is the frequency at which the phase of the closed} \\&\quad \text{loop system is equal to } \pm 180^\circ. \\&\bullet \ \text{In control system the bandwidth of a system roughly measures gain crossover} \\&\quad \text{frequency. The gain crossover is the frequency at which the open-loop gain first} \\&\quad \text{reaches the value 1 and so is } 0.005 \ \text{Hz.}\end{aligned}$$​​