Which of the following terms describes a person who behaves unpredictably?

The term "erratic" accurately describes someone whose behavior is unpredictable and inconsistent. This word originates from the Latin "errare," which means to wander, and in modern usage, it conveys a sense of deviation from the norm or irregularity. When a person is described as erratic, it suggests that their actions or reactions differ significantly from what one might expect, which can create confusion or unpredictability in their interactions with others.

In contrast, the other terms—methodical, predictable, and consistent—imply a level of order, reliability, or regularity. A methodical person follows a systematic approach, while predictable individuals tend to display behavior that can be anticipated based on their past actions. Consistent behavior demonstrates reliability and stability. These characteristics stand in stark contrast to the unpredictability associated with erratic behavior. Thus, "erratic" is the most fitting term to convey the idea of a person whose behavior cannot be anticipated.