Final answer:
The correct option to remove severe stains on stainless steel instruments is organic alkaline detergent, which contains enzymes like proteases and lipases to break down protein, fat, and lipid stains.
Step-by-step explanation:
The correct answer is C. Organic alkaline detergent. Stainless steel instruments can develop severe stains due to the presence of proteins, fats, carbohydrates, and cellulose. Organic alkaline detergents contain enzymes such as proteases and lipases, which can break down and remove these types of stains effectively. For example, proteolytic enzyme detergents can degrade protein-based stains, while lipolytic enzyme detergents are effective against grease and lipid stains.