A Sample Must Contain Many Microorganisms in Order for Them

A sample must contain many microorganisms in order for them to be seen any using microscopy techniques. Why is this so?

A) The area on a microscope slide is very large compared to the relative size of microbes, and you take a very small amount of your sample to place on the slide surface. Therefore, you must have a large number of microbes initially in the culture to increase the chances that you'll be able to see bacteria on the slide.
B) Bacteria are very small. It is only possible to see them if there is a large biofilm of them on the slide. If you don't have a LOT of them, how are you going to see them?
C) This statement is misleading. Microscopy allows us to magnify a specimen to the point where we would be able to visualize even just a few microbes on the surface of the slide. Even if there are only a few microbes in a sample, we could easily visualize them with a microscope.
D) Microscopes only magnify objects on the slide. If you don't have a lot of microbes on the slide surface, you can't magnify the specimen enough to see them as individual cells.
E) When bacteria are placed on a slide, they automatically swarm together into one area of the slide, allowing them to be seen. If there are too few bacteria in the sample, they are unable to swarm effectively and thus cannot be seen, even with staining.