TExES Physical Education EC-12 Practice Exam

Vitamin B-12 plays a critical role in the synthesis of red blood cells, which are essential for transporting oxygen throughout the body. It is involved in DNA synthesis and the proper functioning of the nervous system. Meats, fish, and poultry are among the primary dietary sources of vitamin B-12, making it readily available for those who consume these foods.

In contrast, biotin primarily supports carbohydrate and fat metabolism, and vitamin K is essential for blood clotting processes. Vitamin B-6, while significant for protein metabolism and cognitive development, does not have the same direct role in red blood cell synthesis as B-12 does. Thus, the emphasis on vitamin B-12's specific functions in blood health and its dietary sources establishes it as the correct answer to the question.