In a positive feedback control system, the feedback signal is with respect to the input signal.

Correct option is C

​$$\textbf{Gain Equation in Feedback Systems:} \\[5pt]\text{Gain} = \frac{X_o}{X_i} = \frac{A}{1 - A\beta} \\[15pt]\textbf{Key Characteristics of Positive Feedback:} \\\bullet \, \text{In \textit{positive feedback}, the \textbf{gain is increased} and the \textbf{bandwidth is reduced}.} \\\bullet \, \text{The error signal in positive feedback systems \textbf{diverges}.} \\\bullet \, \text{Such a system is also referred to as a \textbf{"Regenerative circuit"}.} \\[15pt]\textbf{Conclusion:} \\\text{Hence, in a \textbf{positive feedback} control system, the feedback signal is} \\\boxed{\text{in phase}} \\\text{with respect to the input signal.}$$​​