Which of the following is considered a benefit security arrangement?

A benefit security arrangement is a mechanism designed to protect the benefits promised to employees, ensuring that funds are set aside to cover those benefits in the future. Rabbi trusts are specifically designed for this purpose. They allow employers to set aside funds to pay for non-qualified deferred compensation benefits while still allowing the employer some control over the assets. These trusts are irrevocable once established, meaning that they are not easily changed or accessed by the employer, thereby enhancing the security of the benefits owed to employees.

In contrast, 401(k) plans primarily serve as retirement savings vehicles that employees contribute to, rather than a security mechanism for benefits. Health savings accounts (HSAs) are designed to help individuals save for medical expenses, while employee stock purchase plans provide employees the option to purchase company stock at a favorable price but do not serve the same benefit security function. Thus, rabbi trusts stand out as a specific arrangement focused on securing benefits, making them the correct choice in this context.