Explanation: To determine the conditions under which streamline flow is more likely for liquids, we need to analyze the concept of Reynolds number \((R_e).\) The Reynolds number is given by; \(\Rightarrow R_e=\frac{\rho v D}{\mu}\)
where \(\rho=\) density of the fluid, \(v=\) velocity of the fluid, \(D=\) diameter of a pipe, \(\mu = \) dynamic viscosity of the fluid.
We know that the greater the coefficient of viscosity of a liquid, more will be the velocity gradient. So, each line of flow can be easily differentiated. Also, the higher the coefficient of viscosity, the lower the Reynolds number \((R_e).\) Thus, the flow is more likely to be streamlined. Therefore, streamline flow is more likely for liquids with high viscosity and low density.
Hence, option (3) is the correct answer.
