Which of the following is a type of anemia resulting from low vitamin B12 levels?

A. Iron deficiency anemia results from insufficient iron, not vitamin B12, and typically presents with microcytic, hypochromic red blood cells. B. Aplastic anemia occurs due to bone marrow failure, leading to a deficiency of all blood cell types, and is unrelated to vitamin B12 levels. C. Sickle cell anemia is a genetic disorder causing abnormally shaped red blood cells and is not caused by vitamin B12 deficiency. D. Pernicious anemia is a type of megaloblastic anemia caused by vitamin B12 deficiency, often due to the lack of intrinsic factor required for B12 absorption. It results in large, immature red blood cells and can lead to neurological symptoms if untreated.