Use arrows and key terms such as "red blood cells," "oxygen," and "EPO" to describe how high-altitude training helps athletes improve their performance at lower altitudes.

Due to increase red blood cells.

Explanation:

High-altitude training helps athletes to improve their performance at lower altitude because high altitude increases the concentration of red blood cells in the blood. Due to training on high-altitude, the concentration of red blood cell increases in the blood which also increases the consumption of oxygen so when the athletes perform at lower altitude, the more amount of red blood cells in the blood provides natural boost to the muscle due to consumption of more oxygen by the muscle cells.

the law of original horizontality explains:   why rocks appear in layers. correct answer: b the law suggests that all rock layers are originally laid down (deposited) horizontally and can later be deformed.   the principle is used by geologists to make assumptions about the relative ages of sedimentary rocks.

answer: the correct option is d. enzyme

lactase and carbonic anhydrase are the examples of enzymes.

lactase is an enzyme, which is present in the small intestine of mammals. it in the digestion of the disaccharide, lactose ( milk sugar) by converting it into two monosachharide, which are glucose and galactose.

carbonic anhydrase is present in the red blood cells. this enzyme plays significant role in the transport of co₂. it in the conversion of co₂ and h₂o into carbonic acid, which is then dissociated into bicarbonate ions and hydrogen ions.