What type of legal description is Morty using if he references an iron pin and a distance from an oak tree?

The correct choice is the description using "metes and bounds." This method of legal description is characterized by the use of physical features of the geography along with measurements and directions. When Morty references an iron pin and a distance from an oak tree, he is utilizing specific markers and distances that define the boundaries of the land parcel.

Metes refer to the measured distances between points using units of measure (like feet or meters), and bounds refer to the identifiable landmarks that outline the land. In this case, the oak tree serves as a reference point that aids in visualizing the boundaries of the property in a way that is not strictly numerical but rather descriptive of the surrounding environment.

Other types of legal descriptions, such as lot and block, rectangular survey, and plat reference, rely on more standardized or mapped methods rather than the unique and situational characteristics used in a metes and bounds description. These methods often reference plat maps or standardized sections, which contrasts with the personalized nature of using natural features and precise measurements found in metes and bounds descriptions.