Why would an administrator change the value of the spanning-tree priority of a switch?

A.
to force a given switch to become an STP server

B.
in order to optimize the path that frames take from source to destination

C.
in order to allow VLANs to be sent from one switch to another across a single link

D.
to increase the BID, so the switch is more likely to become root bridge

E.
to increase the priority so a designated port will become a root port

Explanation:
The Bridge Priority is used to measure the preference of a bridge in the spanning-tree Algorithm.
The possible values range between 0 and 65,535. The default setting is 32,768. By adjusting the
priority, the root bridge can be manually assigned to meet the needs of the network administrator.