Experimental studies manipulate factors to determine their effects.
An experimental study involves manipulating one variable (called an independent variable) to determine its effect on another variable (a dependent variable). An example of a manipulated variable (independent variable) can be hours of sleep, and the dependent variable (resulting variable) can be speed of reflexes. Hours of sleep (independent variable) can be manipulated (increased or decreased) to see the result it has on speed of reflexes (outcome or dependent variable).
Between the two i think the answer is D. They planted thick trees to trap rain and snow.
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1.The colonists who were against the British began calling themselves "Patriots". in the town of Concord. He had also heard that John Hancock and Samuel Adams, two leaders of the Sons of Liberty, were in Lexington. General Gage sent 700 British soldiers to find the weapons and arrest the two Patriot leaders.
2.Because if they showed up earlier they could have won because they might not have been surrounded, the people wouldn't have been ready for them.