The frequency response of a first order system, has a phase shift with lower and upper bounds given by

A. $$ - \infty ,\,\frac{\pi }{2}$$

B. $$ - \frac{\pi }{2},\,\frac{\pi }{2}$$

C. $$ - \frac{\pi }{2},\,0$$

D. $$0,\,\frac{\pi }{2}$$

Answer: Option D