Final answer:
Option D). Cyanosis is a late sign of hypoxia, characterized by a bluish discoloration of the skin, which occurs after early warning signs like restlessness or anxiety.
Step-by-step explanation:
Cyanosis is the late sign of hypoxia that a patient presents with. When oxygen saturation falls significantly, deoxygenated hemoglobin in blood vessels occurs, resulting in the bluish discoloration of skin and mucous membranes known as cyanosis. Because it follows other earlier signs of hypoxia, like restlessness or anxiety, this is frequently regarded as a late sign. Fatigue, headaches, and confusion are common early signs of hypoxia and are reactions to mild initial oxygen deprivation. The body may exhibit more serious symptoms in cases of severe or protracted hypoxia, such as eupnea, or normal breathing, which may eventually lead to irregular breathing patterns and, in the worst case scenario, cyanosis if the hypoxia is not treated.