The correct statement in respect of protein haemoglobin is that it:

Haemoglobin in blood carries oxygen from the lungs or gills to the rest of the body (i.e. the tissues). There it releases the oxygen to permit aerobic respiration to provide energy to power the functions of the organism in the process called metabolism. Related Theory Four $\mathrm{Fe}^{2+}$ ions of each haemoglobin can bind with 4 molecules of $\mathrm{O}_2$ and it is termed as oxyhaemoglobin. $$ \mathrm{Hb}_4+4 \mathrm{O}_2 \rightarrow \mathrm{Hb}_4 \mathrm{O}_8 $$