A company's sales have been declining for the past three quarters. The manager has decided to implement a new control system to try to improve sales. Which of the following control systems would be the most effective in this situation?
(a) A budget system that sets targets for sales and profits.
(b) A performance appraisal system that evaluates the performance of sales staff.
(c) A quality control system that ensures that products meet customer expectations.
(d) A survey that measures customer satisfaction with the company's products and services.