Answer: Hypoxia
Explanation: hypoxia induces the production of erythropoietin, which is a hormome produced by the kidneys to help increase the productiom of red blood cells in the body. In Jessica's case, she might be experiencing this due to a change in ultitide whereby her body needs more oxygen than it originally gets (crllular hypoxis), therefore, her body signals for more red blood cell production. The erythropoietin will then be secreted and more red blood cells will be formed by the bone marrow through the hormonal action.