$1.$ With regard to compensation, which of the following is true?

A$.$ Companies change their compensation plans more frequently than they change their strategies.

B$.$ Compensation plans should be reviewed frequently to make sure that they are consistent with strategies.

C$.$ Most firms change their compensations plans at least once in two years.

D$.$ Firms should only change their compensation program when the salespeople are dissatisfied.

E$.$ All of these are true