ACD

1) Both Kanban and Scrum are project management frameworks but different in nature-
Kanban continuously delivers tasks until the project is complete, while Scrum delivers chunks of work in set periods called
sprints.
2) Here in question opted framework is SCRUM (so Kanban cannot be answer)

3) Sprint Backog and Product Backlog
A sprint backlog is a subset of the product backlog and lists the work items to complete in one specific sprint. The purpose of
the sprint backlog is to identify items from the product backlog that the team will work on during the sprint.
Both are used in Scrum.

4) Email notifications are good to have functionality

ACD.

Kanban and Scrum are two different Agile delivery methodologies.

ACD is the right answer. Kanban is not mandatory in Scrum

it should be ACD