The correct answer is: D. ideal fluid
An ideal fluid is a theoretical fluid that has no viscosity or resistance to flow. In other words, an ideal fluid is a fluid that flows without friction.
A fluid is a substance that can flow and take the shape of its container. Fluids can be either liquids or gases. Liquids are fluids that have a definite volume but no definite shape. Gases are fluids that have neither a definite volume nor a definite shape.
Viscosity is a measure of the resistance of a fluid to flow. The higher the viscosity, the more resistance the fluid has to flow. Water has a low viscosity, which means that it flows easily. Honey has a high viscosity, which means that it flows slowly.
A perfect solid is a theoretical solid that has no imperfections. In other words, a perfect solid is a solid that is completely rigid and has no defects.
A solid is a state of matter that has a definite shape and volume. Solids are made up of atoms or molecules that are held together by strong forces. These forces prevent the atoms or molecules from moving around freely, which gives solids their shape and volume.
The answer to the question is “ideal fluid” because an ideal fluid is a theoretical fluid that has no viscosity or resistance to flow. This means that an ideal fluid would flow without friction, which is the resistance that a fluid encounters when it is moving.