D because the others harm the bird instead of helping
<span>Anton van Leeuwenhoek learned to grind lenses ( 1668) and develop simple microscopes.
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Leeuwenhoek heated the middle of a small soda glass rod , over a flame. On pulling apart the two ends, the glass rod elongated into thin whiskers .
Heating the end of this whisker resulted in a tiny high quality glass sphere. These glass spheres then became the lens of his microscope, with the smallest sphere providing the greatest magnification.
Leeuwenhoek's designs were very basic. The body of the microscope was a single lens mounted in a tiny hole on a brass plate. The specimen was then mounted on a sharp point that sticks up in front of the lens. It's position and focus could be adjusted by turning the two screws.
The entire instrument was about 3 to 4 inches long and had to be held up close to the eye, requiring good lighting and great patience to use.
Fossils are the remains or impression of the dead animals and plants that lived in the past.
I'm sorry but can you be a bit more specific on these following observations?
