Concept:Pleiotropy means one gene influences multiple unrelated traits. This happens because a single gene's product can affect several body systems.Explanation:A gene codes for a protein that may work in different pathways. For instance, the HBB gene mutation in sickle cell anemia changes red blood cell shape, impacts oxygen transport, and causes organ damage. Similarly, Marfan syndrome (FBN1 gene) affects skeleton, eyes, and heart. This is pleiotropy. It is different from polygenic inheritance, where many genes produce one trait. Understanding pleiotropy helps explain why single-gene disorders often show many symptoms.Answer:Option A: One gene influencing multiple traits