I believe it is b. you only want to change one thing at a time so you know which one thing caused the effect
Solid should be the anwser
C. the number of protons and neutrons an element has in its nucleus
The best answer among the choices given is option A. Chemical weathering of rocks is a source of dissolved substances in the ocean. It is a process that involves the erosion of rocks due to chemical reactions by water and substances dissolved in the water. Therefore, it most likely the source of dissolved substances.