The question is asking about the major metal elements required by the living organisms.

Option 1: Potassium and Calcium are required in major quantities but Manganese and Molybdenum are essential trace elements, needed in smaller amounts.

Option 2: Similar to option 1, Potassium and Calcium are required in abundance but Molybdenum and Copper are needed in smaller quantities, hence this is incorrect.

Option 3: Potassium, Sodium, Magnesium, and Calcium are indeed the major metal elements required by most living organisms. They are vital in a variety of key biological processes like nerve signal transmission (Na, K), muscle function (Ca) and chlorophyll (Mg in plants). This is why it is the correct answer.

Option 4: Sodium, Magnesium are required in major quantities but Copper and Manganese are trace elements- meaning they are required in much smaller quantities, hence this option is not correct.