Who discovered the nucleus?

Explanation: Option B is correct:

• Nucleus: The cell organelle that controls each and every activity of a cell is known as a nucleus.
• The nucleus is the largest cell organelle when compared to other organelles present in the cell.
• The true nucleus is the main characteristic of all eukaryotic organisms.
• The nuclei present in a cell may vary from one to more based on the organism.
• In 1831, Robert Brown first discovered and described the nucleus in the roots of Orchids.

Options A, C, and D are incorrect:

• Matthias Schleiden is known for cell theory.
• Robert Hooke is known for his observation of the dead cells in the cork.
• Richard Altmann is known for the discovery of Mitochondria.

Final answer: The correct answer is option B, that is the nucleus was discovered by Robert Brown in 1831.