Question

why does the heart automatically adjust the flow of blood to match activity levels?
a. extreme activity damages blood cells and the body needs replacements.
b. the heart requires more oxygen when exercising.
c. it reduces the level of oxygen in the blood.
d. organs and muscles require more blood under stress.

please select the best answer from the choices provided.

○ a
○ b
○ c
○ d

mark this and return save and exit next

Explanation:

• Option A: Extreme activity doesn't primarily damage blood cells to need replacements for blood flow adjustment.
• Option B: The heart's oxygen need isn't the main reason for blood flow adjustment to match activity; it's about supplying organs/muscles.
• Option C: The heart adjusts to increase, not reduce, oxygen in blood during activity.
• Option D: During activity (stress on body), organs and muscles need more oxygen and nutrients carried by blood, so heart adjusts blood flow.

Answer:

D. Organs and muscles require more blood under stress.