Living organisms require at least 27 elements of which 15 are metals. Among these, those required in major quantities include

1. Living organisms require numerous chemical elements for survival and function. About 27 are considered essential, including 15 metals. 2. These essential elements are categorized as macronutrients (required in large quantities) and micronutrients (required in smaller quantities). 3. The question asks for metals required in major quantities (macronutrients). 4. Among the options, Potassium (K), Sodium (Na), Magnesium (Mg), and Calcium (Ca) are all considered major metallic elements essential for life. 5. Manganese (Mn), Molybdenum (Mo), and Copper (Cu) are essential metallic micronutrients, required in smaller amounts. 6. Therefore, the combination of Potassium, Sodium, Magnesium & Calcium represents metals required in major quantities.