Which of the Following Is Not Correct Concerning the Oxygenation

Which of the following is not correct concerning the oxygenation plot of proteins X and Y, shown in the graph below?

A) Protein X exhibits tighter oxygen binding than protein Y.
B) Protein Y would function as a better transport protein than protein X.
C) Protein X exhibits cooperative binding; Y does not.
D) Protein X corresponds to myoglobin; protein Y corresponds to hemoglobin.
E) Protein Y contains multiple binding sites.