What characteristics define a main motion in parliamentary procedure?

A main motion in parliamentary procedure is characterized by being debatable and amendable, making option B the correct answer. This means that members of an organization can discuss the merits of the motion before it is voted on, allowing for various viewpoints to be expressed and considered. Additionally, the term "amendable" indicates that modifications can be made to the motion before it is finalized, giving flexibility to the members to refine the proposal based on discussion outcomes. These features are fundamental to fostering active participation and ensuring thorough deliberation in decision-making processes.

In contrast, the other options do not accurately reflect the nature of main motions. For example, requiring a two-thirds vote is typically associated with motions that prohibit something or limit debate, which does not capture the essence of a standard main motion. Similarly, a unanimous vote is not a requirement for a main motion, as that would impose an unrealistic restriction on discussion and decision-making. Lastly, being non-amendable contradicts the primary characteristics of a main motion since the ability to amend is essential to foster a collaborative and responsive environment in parliamentary procedure.