How much work is required of the Developers to complete a Product Backlog Item selected during the Sprint Planning?

How much work is required of the Developers to complete a Product Backlog Item selected during the Sprint Planning?
A . As much as s required to meet the Scrum Team’s Definition of Done.
B. All development work and at least some testing.
C. As much as they can fit into the Sprint with remaining work deferred to the next Sprint.
D. A proportional amount of time on analysis design development and testing.

Answer: A