Briefly explain why ONE of the following was the most significant factor encouraging movement westward in the 1840s and 1850s. Economy
Foreign Policy
Ideology

the right answer for the question that is being asked and shown above is that: "their policy of "divide and rule" pitted political groups against each other to keep any one group from becoming too powerful.  " the  participant in european imperialism is being described below is that  their policy of "divide and rule" pitted political groups against each other to keep any one group from becoming too powerful. 

social contract theory, nearly as old as philosophy itself, is the view that persons' moral and/or political obligations are dependent upon a contract or agreement among them to form the society in which they live

discrimination! they faced a lot of racism

asthenosphere/ lithosphere would be the answer