A Researcher Designs an Experiment by Manipulating the Following Variables

Multiple Choice

A researcher designs an experiment by manipulating the following variables: method of presenting material (visual, auditory) ; difficulty level (easy, difficult) ; and amount of material (low, moderate, high) . For a completely independent groups design with 10 participants per group, how many participants would the researcher need?

A) 80
B) 120
C) 70
D) 60