Answer:C 
Explanation: you should know this 
 
        
                    
             
        
        
        
Answer:
Shifting cultivation is an agricultural system in which a person uses a piece of land, only to abandon or alter the initial use a short time later. This system often involves clearing of a piece of land followed by several years of wood harvesting or farming until the soil loses fertility.
 
        
                    
             
        
        
        
Answer:
As the electorate expanded, the political parties evolved to mobilize the growing mass of voters as the means of political control. Political parties became institutionalized to accomplish this essential task. ... The number of independent or third-party members of Congress or of state legislatures is extremely low
 
        
             
        
        
        
The first computer or ENIAC (Electronic Numerical Integrator Analyzer and Computer) which  the University of Pennsilvania built to do ballistics calculations for the U.S. and other early computers proved to many universities and corporations that these machines were useful because They could solve problems in 30 seconds that otherwise would have taken 12 hours by hand. 
For this reason, most of the first computers in the United States were purchased by universities and corporations in spite of  the space ,manpower and  the tremendous investment of money, they demanded in this early stages.
 
        
             
        
        
        
Mexican immigrants is your answer.
Midwestern farmers traveling to Southwest America would be entering into Mexico (before the Mexican-American War), which included present-day Texas stretching to present-day California.
hope this helps