"which statement concerning the oxygen level in the lake can be inferred from the graphs?
(1)trout and whitefish require higher oxygen levels than do carp.
(2)carp are more sensitive to oxygen levels than are other fish.
(3)the fish in this lake all require the same amount of oxygen for survival.
(4)walleye populations were highest when the oxygen levels were lowest."

After seeing a graph represented below, I have recognized the correct answer, and I think that the statement concerning the oxygen level in the lake which can be inferred from the graphs is being revealed by the option 1 -Trout and whitefish require higher oxygen levels than do carp. As you can see the oxygen line on the graph shows that carp does not require as much oxygen as whitefish does require, as level is increasing on the left side.
Hope you will find it helpful!
Regards.