The county clerk may provide that absent voting shall be either by voting machine or by marking a paper ballot or a combination of both. In any of the foregoing cases he may establish one (1) absent elector unit to handle and process absent elector ballots for each legislative district within his county and shall cause sufficient ballots of the proper kind or kinds to be provided.
Voted ballots shall be retained by the county clerk until election day when they shall be transferred to the ballot processing center and thereafter made a part of the election returns.