Water is flowing through a horizontal tube having cross-sectional areas of its two ends being $$A$$ and $$A'$$ such that the ratio $$A/A'$$ is $$5$$. If the pressure difference of water between the two ends is $$3\times 10^5$$ N m$$^{-2}$$, the velocity of water with which it enters the tube will be (neglect gravity effects)

A

$$5$$ m s$$^{-1}$$

B

$$10$$ m s$$^{-1}$$

C

$$25$$ m s$$^{-1}$$

D

$$50\sqrt{10}$$ m s$$^{-1}$$