A research team is writing a proposal for a quantitative study that will test the efficacy of an ...

A research team is writing a proposal for a quantitative study that will test the efficacy of an online prenatal education module. The team recognizes the need to control for extraneous variables.
 
  Which of the following strategies will best accomplish this goal?
  A) Pairing each member of the experimental group with a member of the control group who shares similar characteristics
  B) Utilizing multiple control groups
  C) Randomly assigning participants to either the experimental group or the control group
  D) Performing the assignment to groups after all participants have completed a pretest