The Pax Romana was a period of peace, unity, & accomplishments that started during Hannibal's reign.
peace, unity, & accomplishments that lasted nearly 200 years.
distrust & conflict between emperors & the Senate.
conquests & fights for control of the empire.

Letter C: Peace, unity and achievements that lasted almost 200 years.

"Pax Romana was a period of peace and prosperity that took place from 27 B.C. to 180 A.D. It aimed to strengthen Roman power in the dominated provinces."

Explanation:

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i think the answer is c, rivers.

explanation:

sometimes, borders fall along natural boundaries like rivers or mountain ranges. for example, the boundary between france and spain follows the crest of the pyrenees mountains. for part of its length, the boundary between the united states and mexico follows a river called the rio grande. the borders of four countries divide africa’s lake chad: niger, chad, cameroon, and nigeria.

i believe your answer is d)