Which option is a correct statement about alternate ports in RSTP?

A. An alternate port receives BDPUs from another port on the same switch and therefore can replace the designated port if it fails.
B. An alternate port receives BPDUs from another switch and therefore can replace the designated port if it fails.
C. An alternate port is always placed in a forwarding state.
D. An alternate port receives BPDUs from another switch and therefore can replace the root port if it fails.

D. An alternate port is a port that is in a discarding state. If the root port fails on the switch with the alternate port, then the alternate port becomes the root port for that switch.