What vitamin is essential in the treatment of pernicious anemia?

Vitamin B12 is essential in the treatment of pernicious anemia because this type of anemia is specifically caused by the body's inability to absorb vitamin B12 due to a lack of intrinsic factor, a protein produced in the stomach necessary for vitamin B12 absorption. Vitamin B12 plays a critical role in the production of red blood cells and the maintenance of the nervous system. In individuals with pernicious anemia, supplementing with vitamin B12 can help reverse the symptoms of anemia and prevent neurological damage that can occur due to B12 deficiency.

The other vitamins listed do not play the same vital role in treating pernicious anemia, as their functions in the body do not encompass the specific need for maintaining healthy red blood cell levels or addressing the absorption issues associated with this condition.