Which of the following is not a common software development methodology?

The correct answer is that "Carousel" is not a recognized or common software development methodology. Agile and Waterfall, on the other hand, are well-established methodologies widely used in the software development industry.

Agile is known for its iterative approach and adaptability, allowing teams to respond quickly to changes and emphasize collaboration with stakeholders. Waterfall, in contrast, follows a more linear and sequential design process, where each phase of development must be completed before moving to the next.

"Carousel" does not have a defined structure or recognition in the same way that Agile or Waterfall do, making it non-standard and not commonly used in software development. Therefore, identifying it as the outlier among the given choices is accurate.