Under a 401(k)plan,what Is Compared to Determine If the Plan

Under a 401(k) plan,what is compared to determine if the plan unfairly discriminates in favor of highly compensated employees?

A) the average percentage of salary made available for the highly compensated to take as cash or to put into the plan is compared to the average percentage of salary made available for other eligible employees to take as cash or to put into the plan
B) the ratio of eligible-to-participate highly compensated employees is compared to the ratio of eligible-to-participate other employees
C) the average percentage of salary deferred by the highly compensated is compared to the average percentage of salary deferred by other eligible employees
D) the percentage of highly compensated employees over age 50 who participate is compared to the percentage of all other employees who participate