A(n) ______ is the most flexible of the grandfathered rights, and it's granted to land that's never been irrigated.

The most flexible of the grandfathered rights in Arizona water law is known as a Type 2 right. This type of right is granted specifically to land that has never been irrigated. The significance of Type 2 rights lies in their ability to allow the holder to utilize water for irrigation purposes over a wider range of potential uses compared to other types of rights.

Type 2 rights are especially valuable because they can be transferred, meaning their holder has a degree of flexibility in how they are used—whether for agriculture or other purposes—offering potential economic benefits. In contrast, Type 1 rights pertain to land that has been historically irrigated and have a set of requirements that may limit their flexibility. Type 3 and Type 4 rights have additional stipulations that reduce adaptability compared to Type 2 rights. Thus, the correct answer reflects the unique nature and utility of Type 2 rights within Arizona’s water law framework.