Which statement best describes echo?

Which statement best describes echo?

A.
Echo is the discernable leak-through of your own Rx path into your own Tx path.

B.
Echo is the discernable leak-through of the packets of your Rx path into your own Tx path.

C.
Echo is the nonaudible leak-through of the packets of your Rx path into your own Tx path.

D.
Echo is the audible leak-through of the packets from the transmit path into your own receive path.

E.
Echo is the nonaudible leak-through of the packets of your Tx path into your own Rx path.