Explanation:

- The entire content of a living cell is known as protoplasm. It includes everything inside the cell, specifically the cytoplasm and the nucleus.

- Option 1: Cell membrane

- This is the outer layer that surrounds the cell, providing protection and structure.

- Option 2: Protoplasm

- This is the correct answer. It refers to the living substance inside the cell, consisting of the cytoplasm and the nucleus.

- Option 3: Mitochondria

- These are the powerhouses of the cell, responsible for energy production, but are just one part of the protoplasm.

- Option 4: Lysosomes

- These are organelles that contain digestive enzymes, playing a role in breaking down waste materials and cellular debris.