Which statement best describe echo?

Which statement best describe echo?

A.
Echo is the nonaudible leak-through of the packets of your 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 descernable leak-through of you own 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 nonaudiable leak-through of the packets of your Tx path into your own Rx path