Which of the Following Is Correct Concerning the Oxygenation Plot

Which of the following is correct concerning the oxygenation plot of proteins X and Y shown below?

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