Question

athletes may take synthetic erythropoietin (epo) to boost their blood calcium levels secretion of growth hormone blood oxygen levels muscle mass

Explanation:

Erythropoietin (EPO) is a hormone that stimulates the production of red blood cells. Red blood cells carry oxygen in the blood. By increasing red blood cell production, synthetic EPO boosts blood oxygen levels, which can enhance athletic performance. Blood calcium levels are regulated by hormones like parathyroid hormone and calcitonin. Growth hormone secretion is controlled by the hypothalamus and pituitary gland. Muscle mass is mainly influenced by factors such as exercise, nutrition, and hormones like testosterone (not directly by EPO).

Answer:

blood oxygen levels