Which of these is an example of an employer using benefits to encourage employees to stay with the company?

a. the employer provides paid time off, which the employee must use in the calendar year.
b. the employer provides benefits which are in line with the standard benefits provided by other employers in the industry.
c. the employer matches the amount of money that the employee pays towards social security.
d. the employer offers stock options, which require the employee to work for a specific amount of time before they vest.