Correct answer B & D.

Explanation:

Fixed-configuration switches, although lower in price, have a designated number of ports and no ability to add ports. They also typically provide fewer high-speed ports. In order to scale switching on a network that consists of fixed-configuration switches, more switches need to be purchased. This increases the number of power outlets that need to be used. Modular switches can be scaled simply by purchasing additional line cards. Bandwidth aggregation is also easier because the backplane of the chassis can provide the bandwidth that is needed for the switch port line cards.

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