What do the presence of fish and a wide diversity of invertebrates in a river indicate?

Which statement is true about the model of the electromagnetic spectrum a: it change the frequencies of light. b: it compare wavelengths of light. c: the color of light waves can be changed using the model. d: the intensities of light waves can be decreased using the model.

The point along a planet's orbit where it is closest to the sun is called the

What are the two basic types of satellites