What type of account is commonly set up through an employer's cafeteria plan in the U.S.?

The correct choice is the Flexible Spending Account (FSA), which is a benefit option frequently offered through an employer's cafeteria plan in the U.S. A cafeteria plan typically allows employees to choose from a variety of pre-tax benefits, promoting tax savings while providing employees with options that best meet their needs.

Flexible Spending Accounts are particularly designed to allow employees to set aside a portion of their earnings before taxes for eligible out-of-pocket health expenses, such as medical, dental, and vision costs. This pre-tax benefit is an attractive option for employees as it reduces taxable income and results in tax savings.

In contrast, while Health Savings Accounts (HSAs) also provide tax advantages for medical expenses, they are specifically available to individuals with high-deductible health plans (HDHPs) and are not commonly classified within the structure of cafeteria plans like FSAs.

Retirement Savings Accounts and Investment Accounts do not fit the description of accounts typically set up within a cafeteria plan. While they are important components of financial planning, they aren't intended to offer the immediate tax benefits associated with health-related expenses like FSAs do. Thus, the focus on pre-tax health expenses makes the Flexible Spending Account the right answer in this context.