For the each of the following studies determine whether a repeated-measures t test is the appropriate analysis. Explain your answers. 

a. A researcher is examining the effect of violent video games on behavior by comparing aggressive behaviors for one group who just finished playing a violent game with another group who played a neutral game.

b. A researcher is examining the effect of humor on memory by presenting a group of participants with a series of humorous and not humorous sentences and then recording how many of each type of sentence is recalled by each participant.

c. A researcher is evaluating the effectiveness of a new cholesterol medication by recording the cholesterol level for each individual in a sample before they start taking the medication and again after eight weeks with the medication.