I'Ve got a question for yous guys Contract Ownable is Context

Question

I'Ve got a question for yous guys Contract Ownable is Context

{
using Roles for Roles.Role ... } (dual access control)

Contract A is ERC20, Ownable {} but has no reference to B.

Contract B is Ownable and is owned by contract A but has no reference to A

Contract B was created during the A deployment but having A registered as it's owner

both contain transferOwnership and are protected by onlyOwner.

Who transfers contract B's ownership 1. Contract A 2. Contract A deployer address?