the plan, participants have the option to transfer assets in their separate defined contribution accounts to the defined benefit portion of the plan in return for service credit under the defined benefit portion, at rates established by the plan sponsor. (e) A legacy plan created under section 805 shall be deemed to have no unfunded vested benefits for purposes of this part, for each plan year following a period of 5 consecutive plan years for which— (1) the plan was fully funded within the meaning of section 805 for at least 3 of the plan years during that period, ending with a plan year for which the plan is fully funded