The CEO of bank A wanted to improve the customers' experience when they visit different branches. The CEO conducted a meeting with the marketing department staff. During the meeting various topics were discussed such as quality of service, performance of employees, the use of technology and digitalization, etc. The CEO wanted to build a linear regression model where he had to determine required variables. Which statement is correct:

a$.$

The quality of service is the response variable and the employee performance is the explanatory variable.

b$.$

The quality of service is the independent variable and the employee performance is the dependent variable.

c$.$

The quality of service is the predictor variable and the employee performance is the explanatory variable.

d$.$

The employee performance is the response variable and the quality of service is the explanatory variable.