Answer:
A. cell wall
Step-by-step explanation:
A cell wall is rigid and is the outermost layer. It also shapes the cell.
A cell membrane is the inner portion of the cell wall and very flexible, not rigid.
The nucleus is not a membrane, it is the center of cell containing genetic information.
The mitochondria is within the cell and it known as the "powerhouse" of the cell.
- Hope that helps! Please let me know if you need further explanation.