What are the important physical features of southern mexico and guatemala

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

What would be the most relevant question to ask to find out why tutankhamen died? what was tutankhamen’s age when he died? was a doctor with tutankhamen at his death? why was tutankhamen mummified after his death? did tutankhamen’s body have evidence of disease?

The economy of the united states is best described as