Water enters through end A with speed \[{{v}_{1}}\] and leaves through end B with speed \[{{v}_{2}}\] of a cylindrical tube AB. The tube is always completely filled with water. In case I tube is horizontal and in case II it is vertical with end A upwards and in case III it is vertical with end B upwards. We have \[{{v}_{1}}={{v}_{2}}\] for

• A.            Case I                                      
• B.            Case II                                     
• C.            Case III                                   
• D.            Each case