The correct answer is D - Planning poker.
Planning poker is a consensus-based estimation technique commonly used in Agile projects. During this technique, team members discuss user stories, clarify details, and independently assign story points. The facilitator (often the Scrum Master) ensures balanced participation. This process encourages team collaboration and reduces estimation bias.
From the PMI Agile Practice Guide:
"Planning poker is a common estimation technique where team members discuss the story, then individually provide estimates using a card deck, reaching consensus over multiple rounds." (PMI Agile Practice Guide, Section 5.3 - Estimation Techniques) Mike Griffiths adds:
"Planning poker is based on Wideband Delphi and allows teams to converge on estimates through discussion and consensus. It is particularly useful for relative estimation of story points." (Mike Griffiths, PMI-ACP Exam Prep Book, Chapter 5 - Adaptive Planning) Why other options are incorrect:
* A (Lessons learned) applies to retrospective activities, not estimation.
* B (Wideband Delphi) is the foundation of planning poker but is more formal and anonymous.
* C (Formal point counting) is not a standard Agile estimation technique.