question: Q:A research scientist attempts to understand the influence of carbon dioxide content in blood on its oxygen binding. The scientist adds carbon dioxide to dog blood and measures the uptake of oxygen in the blood versus oxygen pressure in the peripheral tissue. He notes in one dog that with the addition of carbon dioxide with a pressure of 90 mmHg, the oxygen pressure in the peripheral tissue rose from 26 to 33 mmHg. How can this phenomenon be explained?? 
  {'A': 'Binding of O2 to hemoglobin in lungs drives release of CO2 from hemoglobin', 'B': 'The sum of the partial pressures of CO2 and O2 cannot exceed a known threshold in blood', 'C': 'High partial pressure of CO2 in tissues facilitates O2 unloading in peripheral tissues', 'D': 'High partial pressure of CO2 in tissues decreases peripheral blood volume', 'E': 'High partial pressure of CO2 in tissues causes alkalemia, which is necessary for O2 unloading'},