Question

Which factor affects the heart rate in mammals?

RBC count in blood
Blood type
Need for oxygen

Answer 1

The answer is C: Need for oxygen.

Step-by-step explanation:

Hope this helped ya.

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Answer 2

The answer is Need for oxygen.

You have to imagine your heart as a pump. The more it will pump, the more blood flow will circulate. The more blood flow will circulate, the more oxygen gets transported around the body. This is because oxygen is one of the products that gets transported in blood.