Final answer:
1) peripheral vascular resistance.
The circulatory factor that could contribute to a hypertensive client's elevated blood pressure is peripheral vascular resistance, which is the opposition the heart faces when pumping blood through the arteries.
Step-by-step explanation:
The circulatory factor that could contribute to the client's elevated blood pressure is peripheral vascular resistance. Peripheral vascular resistance refers to the opposition encountered by the heart when pumping blood through the arteries and smaller blood vessels. This resistance is primarily determined by the diameter of the blood vessels and the viscosity of the blood. Factors such as vasoconstriction can increase peripheral vascular resistance, subsequently raising blood pressure.
Age, ethnicity, and respiratory rate are not direct circulatory factors. However, age can indirectly affect blood pressure over time due to changes in vessel elasticity. Ethnicity might correlate with hypertension prevalence due to genetic predispositions and lifestyle factors. Respiratory rate is less directly related to blood pressure and is not typically a circulatory factor affecting hypertension.