The retirement plan that the Birchtree Company offers its eligible employees is a defined contribution plan. With regard to Birchtree's

defined contribution plan, it most likely is correct to say that Birchtree's plan participants

A$.$ Cannot contribute any extra amounts of money to boost the balance of their accounts

B$.$ Do not have emergency access to the funds in their accounts before retirement

C$.$ Always earn a considerably lower investment return than generally is earned by a defined benefit plan

D$.$ Control the investment of their retirement funds and also assume the investment risk