Which of the following is a symptom of shock?

Cyanosis is a symptom of shock that indicates a lack of adequate oxygen in the blood, leading to a bluish discoloration of the skin, particularly in areas with a higher concentration of blood vessels, such as the lips and extremities. This condition arises from insufficient blood flow and oxygen delivery to tissues and organs, which is characteristic of shock.

In scenarios of shock, the body typically reacts by diverting blood to essential organs, resulting in poor perfusion to the skin and extremities. Consequently, a patient may display symptoms such as pallor or cyanosis, rather than warm skin or increased alertness. High blood pressure is also not a common symptom of shock, as shock generally leads to a drop in blood pressure due to volume loss or inadequate pumping capacity of the heart. Increased alertness would contradict the physiological response to shock, as patients often experience confusion or decreased responsiveness during these critical states.