What is cyanosis is due to in Methemoglobinemia, and why does O2 not help this?

a) Increased deoxygenated hemoglobin; O2 is unable to bind to methemoglobin
b) Decreased deoxygenated hemoglobin; O2 is unable to bind to hemoglobin
c) Increased oxygenated hemoglobin; O2 cannot be released from methemoglobin
d) Decreased oxygenated hemoglobin; O2 is unable to bind to methemoglobin