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.
The last one. During the crusades, different foods and such were found, different goods were unlocked to europe, and different mathematic and scientific ideas were brought back as well.
A system in which states agree to form a national government, but maintain their sovereignty
It should be D. because they blockaded the mississippi river.
