Who creates a Product Backlog Item’s estimate?

Who creates a Product Backlog Item’s estimate?
A . The Development Team after clarifying requirements with the Product Owner.
B . The Product Owner with input from the Development Team.
C . The most senior people in the organization, including architects and subject matter experts.
D . The Scrum Master.
E . The Development Team, alone.

Answer: A

Explanation:

According to the Scrum Guide1, Product Backlog refinement is an ongoing activity in which Product Backlog items are reviewed and revised. The Developers who will be doing the work are responsible for sizing or estimating it. The Product Owner may influence them by helping them understand and select trade-offs.