The discovery of the cell was possible do to the invention of the Microscope.
The answer is:
A) light microscope
Looking at the food chain & relationships between organisms can give you a good idea of theoretical cause and effects.
For example:
Starfish are the natural predators of the mussel. If the starfish, that eat the mussels, were to be taken out of the picture: there would most likely be a higher population of mussels.
Polar.
Polar means that it has a negative pole and a positive pole
