The correct answer is B. 
The development of cheap iron in the US was the major factor that lead to the building of skyscrapers. Being able to produce iron cheaply can be contributed to Andrew Carnegie. This American business mogul perfected the Bessemer process in several factories across the eastern part of the US. From there, he was able to sell cheap iron to American businesses for the purpose of growing their empire. 
        
                    
             
        
        
        
When Mexico achieved its independence from Spain in 1821, New Mexico became a province of Mexico, and trade was opened with the United States. ... Two years later, the Treaty of Guadalupe Hidalgo ceded New Mexico to the United States, and in 1853 the territory was expanded to its present size through the Gadsden Purchase.
        
             
        
        
        
Answer: C, the Jordan River is north of the Dead Sea in Israel. 
Explanation: The river flows from Israel and Jordan into the Dead Sea. 
 
        
             
        
        
        
Answer:
B. to comply with international