Final answer:
Potassium is the nutrient crucial for maintaining muscle contraction, found in bananas, raisins, oranges, and potatoes, though it is not one of the provided options. ATP provides energy for muscle contraction, and vitamins like A and K have other vital functions in the body.
Step-by-step explanation:
The nutrient important in the maintenance of muscle contraction and is found in foods like bananas, raisins, oranges, and potatoes is none of the options provided (fats, proteins, vitamins, fiber). Instead, that nutrient is actually potassium, which plays a crucial role in muscle function, nerve signals, and maintaining fluid balance. It is important to note that none of the listed components, fats, proteins, vitamins, or fiber, are primarily responsible for muscle contractions, but they play other significant roles in overall health and body function.
For example, ATP provides energy for muscle contraction, and carbohydrates can be metabolized to produce ATP. Vitamins, like vitamin A and vitamin K, are essential for other body functions such as maintaining connective tissue and aiding in blood clotting, respectively.