Which vitamin is known for its importance in red blood cell formation?

Vitamin B-12 plays a crucial role in the formation of red blood cells. It is essential for the synthesis of DNA, which is required for the production of red blood cells in the bone marrow. Without adequate levels of vitamin B-12, the body cannot produce enough healthy red blood cells, leading to conditions such as anemia. This vitamin also supports the proper functioning of the nervous system and is necessary for the metabolism of every cell in the body, particularly in the brain and in the development and health of nerve cells.

The other options, while important for various bodily functions, do not specifically play the same critical role in red blood cell formation as vitamin B-12. For instance, vitamin B-3 (niacin) is involved in energy metabolism, vitamin C is important for collagen synthesis and immune function, and vitamin D is essential for bone health and calcium regulation, but they do not directly impact red blood cell production in the same way.