Answer: D. advanced technology in irrigation to create agricultural surpluses
Explanation:
There is no map so I do not know which river valley civilization you speak of but I found the options for this question with the answer above being the most likely answer. 
The question most probably alludes to the Indus River Valley Civilization which is one of the oldest civilizations to ever exist in the human world. 
They had quite a high population for the time and so came up with various technological advances to cater for their people including sewage and water systems. 
It was their work with irrigation that earned them high praise however. They came up with advanced irrigation techniques which ensured that agriculture boomed and created enough food to feed the population. 
 
        
             
        
        
        
Don't listen to this doof. the answer is interpersonal racism.
Explanation:
 
        
             
        
        
        
Answer:b. Digital divide
Explanation:
A digital divide refers to how unevenly distributed information and communication technology is between people who come from diffrent groups or backgrounds.
This may occur due to differences in social, geographic or socioeconomic backgrounds.Digital divide refers to a gap in how people access the current technological Information due to the fact that some have no full access to information and technology communication. Examples are access to technology such as computers , telephones ,internet and television.
 
        
             
        
        
        
It is absolutely in Sudan