Which of these is the guideline that a Scrum Master should give?

A Product Owner wants advice from the Scrum Master about estimating work in Scrum.

Which of these is the guideline that a Scrum Master should give?
A . Product Backlog items must be estimated in story points.
B . Estimates are made by the Development Team.
C . Estimates must be in relative units.
D . Scrum forbids estimating.
E . Estimates are made by the Product Owner, but are best checked with the Development Team.

Answer: B

Explanation:

The correct answer is B, because the guideline that a Scrum Master should give is that estimates are made by the Development Team. The Scrum Guide states that “the number of items selected from the Product Backlog for the Sprint is solely up to the Development Team. Only the Development Team can assess what it can accomplish over the upcoming Sprint.” Therefore, the Development Team should estimate the work in Scrum, using any method or unit they prefer.