Question 42 of 75. Ben Elkins, a retired railroad employee, received a Form RRB-1099-R with $18,000 in box 4. What does the box 4 amoun represent? The gross amount of vested dual benefits reduced by repayments. The amount of prior-year repayments. Ben's investment in the plan. The gross amount of non-social security equivalent benefits (NSSEB/tier 2 benefits received, reduced by any benefit repa made during the year. Mark for follow up