Final answer:
An increase in exercise rate would decrease oxygen levels in the blood due to higher oxygen consumption by muscles.
Step-by-step explanation:
An increase in exercise rate would lead to a decrease in the amount of oxygen in the blood. When you exercise, your muscles consume more oxygen than when at rest, this increases the demand for oxygen, and the blood may carry less oxygen as it distributes it to the working tissues more quickly.
Conversely, increasing the inhalation rate or red blood cell count would raise the oxygen levels in the blood, and a larger alveoli surface area enhances the capacity for gas exchange, including oxygen, between the lungs and the blood.