Final answer:
High blood pressure is typically a result of the narrowing of blood vessels or vasoconstriction, which increases resistance and forces the heart to pump harder.
Therefore the correct answer is option is C) Narrowing of blood vessels
Step-by-step explanation:
High blood pressure would be a result of c) Narrowing of blood vessels. Narrowing of blood vessels, or vasoconstriction, leads to an increase in blood pressure because it reduces the diameter through which blood can flow, thus increasing the resistance against the blood flow. This constriction means the heart has to pump harder to push blood through the narrower spaces, raising blood pressure.
In contrast, vasodilation would lead to decreased blood pressure, as the vessels widen, offering less resistance to blood flow. High or low blood volume and cardiac output also affect blood pressure, but in the context of this question, the narrowing of blood vessels is directly associated with increased blood pressure.