Pleiotropy is the term that refers to the situation in which a gene influences more than one trait. Its example is given by

The correct option is A Sickle cell anaemia

Pleiotropy occurs when variation at a single gene locus affects multiple aspects of the phenotype. For persons with an HbS/ HBs genotypes, medical consequences include anaemia, damage to various internal organs including the spleen and heart, and a 'tower' or 'bossed skull'.