A block of mass \(m\) is connected to a light spring of force constant \(k\). The system is placed inside a damping medium of damping constant \(b\). The instantaneous values of displacement, acceleration and energy of the block are \(x, a\) and \(E\) respectively. The initial amplitude of oscillation is \(A\) and \(\omega^{\prime}\) is the angular frequency of oscillations. The incorrect
expression related to the damped oscillations is

1. A \(x=A e^{-\frac{b}{m}} \cos \left(\omega^{\prime} t+\phi\right)\)
2. B \(\omega^{\prime}=\sqrt{\frac{k}{m}-\frac{b^2}{4 m^2}}\)
3. C \(E=\frac{1}{2} k A^2 e^{-\frac{b t}{m}}\)
4. D \(m \frac{d^2 x}{d t^2}+b \frac{d x}{d t}+k x=0\)