(C) Pledges of revenue under division (A) of this section may take any form and may be made subject to any terms that are mutually agreeable between the revenue contributor and the governing board. Pledges may be effectuated through periodic or one-time fixed payments, in variable installments based on estimated increases in tax revenue attributable to the activities of the regional transportation improvement project, or through any other means negotiated by the revenue contributor and the government board. As used in this division, "revenue contributor" means the state, the counties that are parties to the cooperative agreement, or any political subdivision or taxing unit located within any of those participating counties, that pledges revenue to a regional transportation improvement project under division (A) of this section.