Question

which microscope did robert hooke use to study tree bark?
electron microscope
compound light microscope
simple microscope
scanning microscope

Explanation:

Robert Hooke used a compound light microscope. In 1665, he observed cork (tree bark) under this type of microscope and coined the term "cell" as the small compartments he saw resembled the small rooms (cells) in a monastery. Electron microscopes and scanning microscopes are more modern inventions. A simple microscope has only one lens, while a compound light microscope has multiple lenses which gave Hooke better magnification for his observations of tree bark.

Answer:

compound light microscope