How can the user be granted edit permission for cases?

A user has a profile with read-only permissions for the case object.

How can the user be granted edit permission for cases?
A . Create a permission set with edit permissions for the case object.
B . Create a sharing rule on the case object with read/write level of access.
C . Create a public group with edit permissions for the case object.
D . Add the user in a role hierarchy above users with edit permissions on the case object.

Answer: A