Unloading of oxygen from haemoglobin is enhanced under the following conditions

Question

(1) Increase in pH, decrease in $CO_2$, decrease in temperature

(2) Increase in pH, increase in $CO_2$, decrease in temperature

(3) Decrease in pH, increase in $CO_2$, increase in temperature

(4) Decrease in ph, decrease in $CO_2$, increase in temperature