Why is establishing the full set of requirements and their interactions significant?

Establishing the full set of requirements and understanding their interactions is crucial because it directly informs the design options available for a project. Comprehensive knowledge of what is needed and how various requirements relate to each other enables the design team to explore various approaches to meet those requirements. Identifying interactions among requirements helps to foresee potential design constraints or opportunities, ensuring that the final design aligns well with all stakeholder needs.

By having a clear picture of the requirements, designers can innovate and choose among different design paths that cater to the full spectrum of needs, leading to a more robust and effective solution. This foundational understanding ultimately facilitates better decision-making and enhances the overall quality of the final product. Thus, option B reflects the primary reason why establishing a complete set of requirements is of paramount importance in the design definition process.