Which of the following is/are true regarding router operation? A. Routers work at layer 3 only. B. Routers work at layers 1, 2, and 3 to accomplish their tasks. C. Routers only examine layer-3...

A. Routers work at layer 3 only.

B. Routers work at layers 1, 2, and 3 to accomplish their tasks.

C. Routers only examine layer-3 addresses.

D. Routers must examine the layer-2 address to accept the frame first, and then afterward will look at the layer-3 address.