What type of anemia is associated with a deficiency of vitamin B12?

C. Pernicious anemia is the correct answer as it specifically refers to a type of macrocytic anemia caused by a deficiency of vitamin B12, which is often due to the inability of the body to absorb this vitamin due to a lack of intrinsic factor. Intrinsic factor is a protein produced in the stomach that is essential for the absorption of vitamin B12 in the intestines. In pernicious anemia, the autoimmune destruction of gastric cells that produce intrinsic factor leads to impaired absorption of vitamin B12, ultimately causing anemia.

The other types of anemia listed do not directly relate to a deficiency in vitamin B12. Microcytic anemia is typically associated with iron deficiency, hemolytic anemia involves the premature destruction of red blood cells, and aplastic anemia is characterized by the failure of the bone marrow to produce sufficient blood cells due to various causes, including autoimmune diseases or exposure to certain toxins. Understanding the nuances of vitamin B12 and its role in the body helps clarify the specific nature of pernicious anemia as it relates to nutritional deficiency.