Which of the following is the example of pleiotropic gene ; -

A pleiotropic gene is a single gene that affects several different characters (phenotypic traits).
In sickle cell anaemia, a single mutant gene ($Hb^S$) changes the $\beta$-globin chain of haemoglobin. This one change causes many effects: sickle shaped RBCs, anaemia, blockage of blood vessels, pain, damage to organs such as the spleen, kidneys and brain, and resistance to malaria.
(Phenylketonuria is another classic example.)
So sickle cell anaemia is an example of a pleiotropic gene.