The following is a characteristic of a retirement plan that meets the qualifications of Code Sec. 401: The plan may discriminate in favor of highly compensated employees. The plan may not engage in transactions with a disqualified person because it must be operated for the exclusive benefit of the participants and their beneficiaries. Any employee who has attained 21 years of age and completed one year's service must be allowed to participate. Two of the above. All of the above