Read the passage given below and answer the questions (Q. Nos. 143–150) that follow:

The next morning, as I was about to leave the city, I saw peacocks on every tree, rock and hill. Their movements had the same peace, the same grace and the same beauty. As the evening shadows deepened, the air was filled with the song of peacocks. I thought they were there to both welcome and bid me farewell.

Whenever I recall that trip, my mind is filled with the images of those peacocks. I am surprised. Did I really see so many of them? Did the peacocks of Rajasthan actually come out to greet me? I wonder how they are now.

I try to imagine that city now, but all I can see is a picture of desolation. Shocked and disturbed, I am neither able to see the peacocks nor hear their song. Where have they all disappeared? In which corner of the world are they hiding? Suddenly, I have a vision of a lonely peacock on a distant hill. He seems battered and bruised. I walk quickly toward him but, before I can reach the hill, he rises into the sky screaming with terror and disappears.

Where has he gone? Where are his companions, those countless peacocks? Why is he sitting alone on that hill, the very picture of desolation? Why is he so despondent, so terrified? The sight of that dejected, bewildered peacock suddenly brings to mind another image of desolation that I had forgotten. On the far edge of a dark, oil-soaked sea, I see a forlorn duck covered with foul effluents, watching the waves in disbelief. Till yesterday, the sea was ambrosia, today it is poison. The wings of the duck are so heavy with slime that he can no longer fly. Poison flows through the veins in his body.

Identify the clause of the underlined part :
“On the far edge of a dark, oil-soaked sea, I see a forlorn duck...”