Which river forms part of the boarder between mexico and the us

Can someone me choose a broad topic and area of focus i am really doing this as a tally to see which one most people pick ok water pollution global warming endangered species atmosphere for the !

Find the coordinates of a if b(-9,-10) is the midpoint of ac and c has the coordinates of (-1,9)

Which of the following characteristics define a state? check all that apply. a. a population of people b. a sovereign government that determines how a group of people is ruled c. an army, military, or police force d. a territory with set borders