Which estimation technique can be used in Agile Delivery Approach to size the User Stories during Sprint Planning?

A. Product Owner’s relative estimate of the effort that will be needed to implement the User Story

B. Detailed bottom-up effort estimate that breaks each User Story up into hours or shorter tasks

C. Relative estimate in Ideal Person Days that reflects the best estimate provided by the project team

D. Detailed bottom-up effort estimate by the Scrum Master in Story Points based on the User Story complexity