<span>El Nino
</span>A change in the water temperature of the eastern Pacific Ocean that produces cooler than usual surface water temperatures. An unusually long period during which rainfall is below average. Used by NOAA to collect data to predict an El Nino<span>.</span>
Answer: Its "D"
Explanation:
the answer is D due to lakes rivers and mountains being natural barriers. Which in turn creates a boundary between to states or countries.
<span>77.45 million (2013) according to google
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