Which of the following conditions leads to tissue hypoxia without alteration of the oxygen content of blood?

In Cyanide poisoning, there is histotoxic hypoxia. O2 content of aerial blood is normal; however tissues are not able to utilize oxygen. In CO poisoning, O2 cannot bind with Hb as CO competes with O2 for the same binding sites on Hb. O2 content of blood will decrease. Methemoglobin formation is due to poisoning with chlorates, nitrites, or ferricynides. In methemoglobin, Iron is Fe3+ instead of Fe2+. It cannot combine and transpo O2 in normal amounts. O2 content of blood will decrease. Respiratory acidosis as a result of hypoventilation will also be associated with hypoxia; O2 content of blood will be less.