The scatterplot on the right was created as part of a study evaluating the relationship between estimated life expectancy at birth (as of 2014) and percentage of internet users (as of 2009) in 208 countries for which such data were available. (a) describe the relationship between life expectancy and percentage of internet users. (b) what type of study is this? (c) state a possible confounding variable that might explain this relationship and describe its potential effect.