How are ports scaled on vSphere Standard Switches (vSS)?

How are ports scaled on vSphere Standard Switches (vSS)?

A.
Ports on a vSS can be dynamically scaled up and down.

B.
Ports on a vSS can only be statically scaled up or down.

C.
Ports on a vSS can only be dynamically scaled down.

D.
Ports on a vSS can only be dynamically scaled up.

Explanation:
To ensure efficient use of host resources on hosts running ESXi 5.5 and later, the number of ports of standard switches are dynamically scaled up and down. A
standard switch on such a host can expand up to the maximum number of ports supported on the host.
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