Which of the following descriptions matches the term 'cyanosis'?

Choice A reason: Pale skin color is referred to as pallor. This occurs due to a decrease in the number of circulating red blood cells or reduced blood flow to the skin, commonly seen in conditions like anemia, shock, or local arterial insufficiency. It is distinct from the blue tint seen in cyanosis. Choice B reason: A yellowish discoloration of the skin, sclera, and mucous membranes is known as jaundice or icterus. This condition is typically caused by elevated levels of bilirubin in the blood, often signaling hepatic dysfunction, biliary obstruction, or excessive hemolysis of red blood cells. Choice C reason: Redness of the skin is termed erythema. This is caused by hyperemia, or increased blood flow to the capillaries near the skin surface, often due to inflammation, fever, or localized infection. Purple tones may indicate ecchymosis or deep tissue injury, rather than a lack of oxygen. Choice D reason: Cyanosis is a clinical sign characterized by a bluish or grayish tint to the skin and mucous membranes. This occurs when the concentration of deoxygenated hemoglobin in the peripheral capillaries exceeds 5 g/dL, indicating that the tissues are not receiving adequate oxygen from the blood.