Consider a typical stop-and-wait ARQ data link protocol (i.e. using only positive acknowledgments).

When is it possible for the receiver to receive a duplicate copy of the same data frame?

Select one:

a.

If the receiver is busy.

b.

If a previous data frame has been lost.

c.

The sender has no more data to transmit, so it sends the last frame again.

d.

If the receiver's window is full.

e.

If an acknowledgement frame has been lost