Susan has twelve subjects drop out of her study. Which threat to internal validity must she consider?

In order to make it hard for poor blacks to vote without falling afoul of the Fifteenth Amendment, many southern states required citizens to pay __________, which disproportionately disenfranchised African Americans

Fill in the blank with the correct words.

Which of the following countries is the second-largest economy, based on its gross domestic product in 2014?

a. China b. France c. Japan d. Germany