<prompt> The oxygen--hemoglobin dissociation curve is sigmoid becauseBinding of one oxygen molecule increases the affinity of binding other 02 moleculeBinding of one oxygen molecule decrease the affinity of binding other 02 moleculesOxygen affinity of Hemoglobin decreases when the pH of blood fallsBinding of oxygen to Hemoglobin reduces the affinity of Hb for CO2  <response>: Binding of one oxygen molecule increases the affinity of binding other 02 molecules 