Which of the following conditions can cause elevated blood pressure?

All of the listed conditions — dehydration, anxiety, and chronic pain — can indeed lead to elevated blood pressure.

Dehydration causes a decrease in blood volume, which can initially lower blood pressure, but as the body attempts to compensate for this deficit, it can lead to increased heart rate and vasoconstriction, ultimately resulting in elevated blood pressure.

Anxiety engages the body's stress response, stimulating the release of stress hormones like adrenaline and cortisol. These hormones increase heart rate and constrict blood vessels, thus raising blood pressure as part of the body’s fight-or-flight response.

Chronic pain can also elevate blood pressure because persistent pain triggers a stress response that may increase sympathetic nervous system activity, resulting in vasoconstriction and higher blood pressure over time.

Therefore, since all these conditions can raise blood pressure through different mechanisms, selecting "All of the above" reflects the understanding that multiple factors can contribute to this physiological change.