Which of the Following Is Not Cited as a Limitation

Which of the following is not cited as a limitation of merit-based pay?

A) They are typically based on an annual performance appraisal and thus are only as valid as the performance ratings.
B) The pay raise pool fluctuates on economic or other conditions that have little to do with individual performance.
C) Unions typically resist merit pay plans.
D) People are paid according to seniority.