Fill in the blanks to complete the passage about experiments with independent variables that cannot be manipulated. While a(n) - includes a manipulated independent variable in order to see the change in a dependent variable, a(n) - includes an independent variable that cannot truly be manipulated by the experimenter. Because participants cannot be randomly assigned to levels of the independent variable, this type of research has - . posttest-only designquasi-experimentnonequivalent control groupssmall-N designexperimentinterrupted time-series design