The brown stuff is called plaque. This forms on your teeth when you eat and its something you can't get rid of. There is tooth paste that can help maintain it.
Answer:
Food source and space.
Explanation:
With more animals, more food and space is required. With a sudden growth there may not be enough sufficient.
The food source could quickly run out, and same with space.
Answer:
The difference between a radio wave and X- ray is that Radio waves have a much longer wavelength when it's in visible light. x-rays have a smaller wavelength and higher frequency compared to visible light.
Explanation:
