Bill Received a Poor Performance Evaluation in His Job Last

Multiple Choice

Bill received a poor performance evaluation in his job last year. Since then, Bill has started working through his lunch hour, taken on four special projects, and enrolled in night classes to upgrade his computer skills. If Bill receives a better evaluation at his next performance, it will be hard for him to figure out why because ​

A) he failed to use a double-blind procedure to test his hypothesis.
B) he didn't formulate a research hypothesis before implementing the changes. ​
C) none of the actions he took are likely to be related to his overall job performance.
D) the three actions he took are confounded with each other. ​