Which two options are available to ensure that the upgraded switch will be compatible with these hosts?

An administrator is upgrading a vSphere Distributed Switch. The existing switch is version
5.0 and the administrator wants to upgrade to the latest version possible. The environment contains
several ESXi 5.1 hosts.
Which two options are available to ensure that the upgraded switch will be compatible with these
hosts? (Choose two.)

A.
Upgrade the vSphere Distributed Switch to 5.5

B.
Upgrade the ESXi 5.1 hosts to version 5.5, then upgrade the vSphere Distributed Switch to 5.5

C.
Upgrade the vSphere Distributed Switch to 5.1

D.
Upgrade the ESXi host switches to 5.5, then upgrade the vSphere Distributed Switch to