The correct answer is B. Nucleus.
The nucleus is the largest organelle in a eukaryotic cell. It is surrounded by a double membrane and contains the cell’s DNA. The nucleus is responsible for controlling the cell’s activities and for storing its genetic information.
Chloroplasts are organelles found in plant cells. They are responsible for photosynthesis, the process by which plants use sunlight to convert carbon dioxide and water into glucose and oxygen.
Vacuoles are large, fluid-filled sacs found in plant and animal cells. They are responsible for storing food, water, and waste products.
Lysosomes are small, membrane-bound organelles found in animal cells. They contain enzymes that break down proteins, carbohydrates, lipids, and nucleic acids.
The nucleus was first discovered in 1831 by Robert Brown. He observed that plant cells contained a large, spherical structure that he called the nucleus. The nucleus was later found to be present in all eukaryotic cells.