Ans. D. Histotoxic anoxiaHypoxia or Anoxia O2 deficiency at the tissue level Type:a. Hypoxic Hypoxia (anoxic anoxic)i. PO2 of arterial bloodii. Chemoreceptor stimulatedb. Anaemic Hypoxiai. Arterial PO2 is normal but amount of Hb available to carry O2 is reducedii. Chemoreceptors are not stimulated, since dissolved O2 in blood is enough to keep these receptors normal.c. Stagnant or ischemic hypoxiai. Normal PO2 and Hb cone.ii. Blood flow to tissue is so slow that adequate O2 is not deliverediii. Chemoreceptor are strongly stimulated.d. Histotoxic Hypoxia: -i. Caused by Cyanide, that inhibit cytochrome oxidase (cyt aa3), so that tissue cells cannot make use of O2 .ii. O2 delivery to tissue is normal.iii. Chemoreceptor are strongly stimulated.