For similarity, in addition to models being geometrically similar to prototype, the following in both cases should also be equal__________________?

• A. ratio of inertial force to force due to viscosity
• B. ratio of inertial force to force due to gravitation
• C. ratio of inertial force to force due to surface tension
• D. all the four ratios of inertial force to force due to viscosity, gravitation, surface tension, and elasticity