What is the effect of $pCO_{2}$ on oxygen transport?

The oxygen-hemoglobin dissociation curve shifts to the right due to a decrease in which of the following?

Explain the oxygen dissociation curve. Explain the factors required for the transport of $O_2$ by it.

Blood is a medium to transport $O_{2}$ and $CO_{2}$. About ...$A$... per cent of $O_{2}$ is transported by ...$B$... in the blood and the remaining ...$C$... per cent of $O_{2}$ is carried in a dissolved state through the ...$D$...
Select the right options for $A, B, C$ and $D$ to complete the given statement.

Haemoglobin $(Hb)$ transports oxygen from the lungs to tissues. The partial pressure of oxygen in the lungs is different from that in the tissues. Each $Hb$ can bind to up to four oxygen molecules. Suppose we have an equal number of $Hb$ and oxygen molecules,and all the oxygen molecules are in a bound form. Then,which of the following is true?

Which is called Hamburger shift?