Which scientist invented the very first optical microscopes and was also the first person to view single-celled organisms living in pond water? a) robert hooke b) theodor schwann c) mattias schleiden d) anton von leeuwenhoek

The correct answer is option D, that is, Anton Von Leeuwenhoek.  

Anton Von Leeuwenhoek was the first individual to witness living cells. In 1675, he observed a single cell species in a drop of water. These living organisms were microscopic and could only be observed with the help of a microscope.  

Leeuwenhoek was the first person to discover the living cell, as the cell witnessed by Robert Hooke provided no clue of the nucleus and another organelle within the cell. Leeuwenhoek was the first man who found a living cell and observed it under a microscope, providing an indication about the nucleus and all the protoplasmic organelle found in the cell.  

nucleus

would be most reasonable answer tbh