A manometer connected to a closed tap reads \[4.5\times {{10}^{5}}\] pascal. When the tap is opened the reading of the manometer falls to \[4\times {{10}^{5}}\] pascal. Then the velocity of flow of water is [Kerla PET 2005]

• A.            7 \[m{{s}^{-1}}\]                 
• B.            8 \[m{{s}^{-1}}\]
• C.            9 \[m{{s}^{-1}}\]                 
• D.            10 \[m{{s}^{-1}}\]