A means of water erosion would not be C. natural water springs. Erosion occurs when water or wind removes rock, dissolved material, and soil from one location to another. All the other options describe water moving from one location to another, which accurately describes what erosion does.
All of the listed have the same amount of nutrients unless dried or affected in some other way not said.
The immune system<span> is made up of a network of cells, tissues, and organs that work together to protect the body. One of the important cells involved are white blood cells, also called leukocytes, which come in two basic types that combine to seek out and destroy disease-causing organisms or substances.</span>