Which is a correct statement about backup ports in RSTP?

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

A. A backup port is a port in a discarding state. It receives BPDUs from another port on the same switch. If the forwarding port fails, then the backup port will become designated so that connectivity to the segment can be restored.