Plz I need help with 3 and 4

3 d is the correct answer but I am not sure about answer 4 I think the answer should be ans4d because Your kidneys remove wastes and extra fluid from your body. Your kidneys also remove acid that is produced by the cells of your body and maintain a healthy balance of water, salts, and minerals—such as sodium, calcium, phosphorus, and potassium—in your blood. That helps it to stay balance

which ever one is showing doing the same exercise in time intervals such as 30 seconds or a minute several times.