What is relative permeability?

• A. It is the ratio of effective permeability over the absolute permeability
• B. It is the ratio of absolute permeability over the effective permeability
• C. It is the ability to flow fluid through the porous media of permeable rock when only one type of fluid is in the rock pore spaces
• D. It is the ability to flow fluid through the porous media of permeable rock when more than one type of fluid is in the rock pore spaces