Explanation/Reference:
Explanation:
First we should grasp the concept of BECN & FECN through an example:

Suppose Router A wants to send data to Router B through a Frame Relay network. If the network is
congested, Switch 1 (a DCE device) will set the FECN bit value of that frame to 1, indicating that frame
experienced congestion in the path from source to destination.
This frame is forwarded to Switch 2 and to Router B (with the FECN bit = 1). Switch 1 knows that the
network is congesting so it also sends frames back to Router A with BECN bit set to 1 to inform that path
through the network is congested.

In general, BECN is used on frames traveling away from the congested area to warn source devices that
congestion has occurred on that path while FECN is used to alert receiving devices if the frame
experiences congestion.
BECN also informs the transmitting devices to slow down the traffic a bit until the network returns to normal
state.
The question asks "which output value indicates to the local router that traffic sent to the corporate site is
experiencing congestion" which means it asks about the returned parameter which indicates congestion -
>BECN.