In an experiment, Dr. Fatka watches forty participants play basketball and gives each participant a ...

In an experiment, Dr. Fatka watches forty participants play basketball and gives each participant a rating from 1 to 10 to assess the participant's basketball ability. Dr. Fatka randomly divides the forty participants into two groups and personally teaches one group how to play basketball and the other group how to play football. Finally, Dr. Fatka watches all forty participants play basketball again and gives each participant a new rating. After looking at the data, Dr. Fatka concludes that teaching basketball is more effective than teaching football in raising the basketball ratings. This experiment is flawed because of ____.
 
  a. experimenter bias
  b. random sampling
  c. double-blind design
  d. correlations