Final answer:
Crescent-shaped hemoglobin is found in sickle cell anemia, where red blood cells take on a sickle shape, causing health issues due to obstruction of blood flow. The correct option is D.
Step-by-step explanation:
The type of anemia in which you might find crescent-shaped hemoglobin is sickle cell anemia. In sickle cell anemia, there is a production of an abnormal type of hemoglobin called hemoglobin S. This causes erythrocytes, or red blood cells, to assume a characteristic sickle or crescent shape, particularly under low oxygen concentrations.
These abnormally shaped cells can get lodged in narrow capillaries, blocking blood flow and leading to various health issues. Sickle cell anemia is a genetically inherited condition more commonly found in individuals of African descent.