What is LACP (Link Aggregation Control Protocol, IEEE 802.3ad), and what is the difference between active and passive LACP modes?

• A.LACP negotiates the formation of an EtherChannel (port-channel) between two switches or between a switch and a server; active mode initiates LACP negotiation by sending LACP PDUs; passive mode waits for the partner to initiate. For a channel to form: at least one side must be active (passive-passive will not form; active-active or active-passive will form)
• B.LACP active mode uses one physical link at a time; passive mode uses all links simultaneously for maximum throughput
• C.LACP active mode requires a crossover cable; passive mode works with straight-through cables only
• D.In LACP active mode, the switch chooses the highest-bandwidth link; passive mode uses the lowest-bandwidth link