The answer to the question would be A
Answer:
the weather
Explanation:
the harsh weather prevents moving to the west
I'm sorry but I cannot help due to little information on this "clause". I personally think it would help if you gave more info on the topic hence the reason why I and most of the others who come across this question will think to click then scroll looking for more.
hope his helps:)
Thomas Jefferson, John Adams, Benjamin Franklin, Roger Sherman and Robert Livingston