Which of the following is a key aspect of the Agile project management methodology?

Test-driven development (TDD) is a software engineering practice focused on writing tests before code - it is not a defining feature of Agile project management methodology itself.

Daily standup meetings, known as the Daily Scrum in Scrum methodology, are a fundamental Agile practice that keeps the team aligned and surfaces impediments quickly. Each team member addresses what they completed, what they plan to do next, and what is blocking them, typically time-boxed to 15 minutes. This ceremony is a universally recognized key aspect of Agile project management across frameworks including Scrum, Kanban, and SAFe.

Agile uses short iterations called sprints, but the overall project duration is not necessarily short - large Agile programs can span years across many successive sprints.

A fixed, fully defined list of requirements is a hallmark of Waterfall methodology; Agile explicitly embraces evolving requirements and uses a prioritized, flexible backlog instead.