Final answer:
A decrease in pH and an increase in temperature are conditions that would shift the hemoglobin-oxygen dissociation curve to the right.
Step-by-step explanation:
A decrease in pH (answer a) and an increase in temperature (answer b) are conditions that would shift the hemoglobin-oxygen dissociation curve to the right. When the level of carbon dioxide in the blood increases, more hydrogen ions are produced, leading to a decrease in pH. This decrease in pH reduces the affinity of hemoglobin for oxygen, causing the oxygen dissociation curve to shift to the right. Similarly, an increase in body temperature, such as from increased muscle activity, also reduces the affinity of hemoglobin for oxygen and causes the curve to shift to the right.