The correct answer is option 3, "Cell wall".

1. Cell membrane: The cell membrane is present in both plant and animal cells. It is a thin, flexible barrier that surrounds the cell, protecting it and controlling the movement of substances in and out of the cell.

2. Endoplasmic reticulum: The endoplasmic reticulum is also found in animal cells. It is a network of membranes that is involved in the synthesis, folding, and transport of proteins.

3. Cell wall: This organelle is not found in animal cells. The cell wall is a rigid structure that is present in plant cells, fungi, and bacteria. It provides support and protection to the cell.

4. Lysosome: Lysosomes are present in animal cells. They are small vesicles filled with digestive enzymes that break down waste materials and cellular debris.

Therefore, the correct answer is option 3, "Cell wall", as it is not found in animal cells.