Final answer:
Vitamin B6 is the vitamin stored primarily in muscle tissue, offering a reserve for the body to use when needed.
Step-by-step explanation:
The vitamin stored primarily in muscle tissue is vitamin B6. When you consume vitamins, they can be either fat-soluble or water-soluble. The fat-soluble vitamins, such as A, D, E, and K, can accumulate in the body's lipid stores. Vitamin B6, while not a fat-soluble vitamin, is unique because it is stored mainly in muscle tissue, offering a reserve that the body can draw upon when dietary intake is insufficient.