Concept:For an incompressible fluid, the equation of continuity states that the volume flow rate remains constant.A1V=A2V1where A1 and A2 are the cross-sectional areas of the pipe and the nozzle, respectively.Explanation:Since water is incompressible, the volume of water passing per second through the pipe must equal that through the nozzle.The internal diameter of the pipe is d, so its area of cross-section is:A1=4πd2Let the diameter of the nozzle be D.Then the area of cross-section of the nozzle is:A2=4πD2Using the equation of continuity:4πd2V=4πD2V1Cancel the common factor 4π from both sides.d2V=D2V1Rearranging for D2:D2=V1d2VTaking the square root on both sides:D=dV1VThus, the diameter of the nozzle is directly proportional to the pipe diameter and depends on the ratio of speeds.Answer:The diameter of the nozzle is dV1V.Hence, the correct option is A.