How does carbon monoxide inhibit the transport of oxygen?

The dissociation curve is associated with

What is the shape of the oxygen dissociation curve of hemoglobin?

What is the amount of oxygen carried by $1 \, g$ of hemoglobin?

Bulk of carbon dioxide $(CO_2)$ released from body tissues into the blood is present as

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?