What are the possible reasons for this?

Universal Containers uses a Private Sharing model for Account. User A is on-boarded to User B’s team and given the same profile and Role Both users own 20 Accounts but user User B is a able to see 40 Accounts whereas User A can only see the 20 that the own.

What are the possible reasons for this?
A . User B is a member of a Group that gained access to the records through a Sharing Rule.
B . User B had the records manually shared with them.
C . User B is a member of a Queue that gained access to the records through a Sharing Rule
D . User B had the records shared with them through a Permission Set.

Answer: D