What process involves separating water from its mineral substances, such as calcium and magnesium?

The correct process for separating water from its mineral substances, particularly calcium and magnesium, is distillation. Distillation involves heating water to create steam, which is then cooled to collect the pure water while leaving behind the minerals and impurities. This method is effective because it takes advantage of the differing boiling points of water and various minerals, allowing for the collection of purified water.

Filtration, while a method of separating solids from liquids, does not specifically target the separation of dissolved minerals from water, as many dissolved substances can pass through a filter. Evaporation refers to the process of turning a liquid into vapor, which could also leave impurities behind, but it does not directly collect pure water. Decantation involves pouring off a liquid from a settled solid but is not effective for dissolved minerals in water. Thus, distillation is the most suitable choice for separating water from its mineral content.