I think it is ovulation..
A) a slight decrease in the use of public transportation throughout the country.
Because at any time, you can find cells that are undergoing mitosis.
Answer:
oxygen , carbon , hydrogen , nitrogen , phosphorus , sulfur are some examples
The answer is #4. The first and second one involve acid, which is chemical weathering. The third one involves oxidation, which is a chemical process. The only mechanical process is option four.
