A block $M$ hangs vertically at the bottom end of a uniform rope of constant mass per unit length. The top end of the rope is attached to a fixed rigid support at O. A transverse wave pulse (Pulse 1) of wavelength ${\lambda }_0$ is produced at point O on the rope. The pulse takes time $T_{OA}$ to reach point A. If the wave pulse of wavelength ${\lambda }_0$ is produced at point A (Pulse 2) without disturbing the position of M it takes time $T_{OA}$ to reach point O. Which of the following options is/are correct?

1. A The velocity of any pulse along the rope is independent of its frequency and wavelength
2. B The velocities of two pulses are the same at the midpoint of rope
3. C The wavelength of pulse 1 becomes longer when it reaches point A
4. D The time $T_{AO}=T_{OA}$