Answer:
Right answer:
C. 4.6 billion years old.
Explanation:
Scientist bgan to really observe the world around them
Answer:
Bacteria help protect the cells in your intestines from invading pathogens and also promote repair of damaged tissue. Most importantly, by having good bacteria in your body, bad bacteria don't get a chance to grow and cause disease.
I believe it would be B due to the fact that certain time periods being and end at certain times
