Why do you think the sumerians were attracted to the land. between the tigris and euphrates rivers

In which research method does a researcher change the value of one variable to determine how the change affects another variable? a. experiment b. observational research c. survey d. case study

"“forty or fifty years ago, many people thought that simply transferring technologies from industrialized to developing countries would close the technology gap. now we know that technologies developed in industrialized countries may not be suitable for use in other environments. they may require a particular type of infrastructure to operate. they may need specialized parts or knowledge to mend when they break we now understand that innovative capacity must be built in different ways." - united nations secretary-general ban ki-moon based on the secretary general's comments, which of these would be most important for a country to improve? a) native literature b) transportation grid c) cultural traditions d) construction styles

This chart shows the number of soldiers killed according to two different sources. source a is a book written by university professors. source b is from a well-known historical website. in a paragraph, explain why the data presented is different, and evaluate the reliability of each source. which should be used in a school research project, and why?