An executive coach started working with employees at Agency X one month ago, and since then, Agency X's employees have drafted 50% more reports. It is clear that the coaching has helped Agency X's employees write more reports. Which of the following statements, if true, would most strengthen the above argument? 

a. Since Agency X hired the executive coach, the reports its employees have had to write are less complex than they were previously.

b. Agency X has hired many new employees in the last month. 

c. Agency X has renewed the executive coach's contract for another year. 

d. Agency Z hired this executive coach last year and also saw a significant increase in the number of reports written. 

e. The employees at Agency X have had less work to do in the last month than usual.