What best defines "opportunity cost"

Could you find out how im still getting an 83 percent on this in edhesive a = input("enter an animal: ") s = input ("enter a sound: ") e = "e-i-e-i-o" print ("old macdonald had a farm, " + e) print ("and on his farm he had a " + a + "," + e) print ("with a " + s + "-" + s + " here and a " + s + "-" + s + " there") print ("here a " + s+ " there a " + s) print ("everywhere a " + s + "-" + s ) print ("old macdonald had a farm, " + e)