Pick out the correct statement pertaining to transition$/$ entrance length in fluid flow.

A$.$ The length of entrance region of pipe, in which full development of fluid flow takes place such that velocity profile does not change downstream, is called the transition length

B$.$ Transition length for laminar flow of Newtonion fluids in a pipe of diameter $\text{'}$d$\text{'}$ is equal to $0\mathrm{.}05.$ D$.$NRe

C$.$ Transition length for turbulent flow of Newtonion fluids in a smooth pipe of diameter $\text{'}$d$\text{'}$ is equal to $50$ D

D$.$ All of the above