During physical exercise and activities, the rate of breathing and heart increases, and as a result, the arteries dilate. Thus, option D is the correct blank.
Heart rate is the indication of the heart beats per minute to efficiently pump the blood in the body. Similarly, the breathing rate is gases exchanged in the time period.
The heart and breathing rate increase during the exercise as more energy is needed by the body. On the other hand, the arteries dilate to pump the required blood efficiently.
Therefore, the rate increases, and the arteries dilate.
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