(a) Acquisition by a Class III rail carrier of rail property that would be operated by a third party;
(b) Operation by a Class III carrier of rail property acquired by a third party;
(c) A change in operators on such a line; and
(d) Acquisition of incidental trackage rights. Incidental trackage rights include the grant of trackage rights by the seller, or the acquisition of trackage rights to operate over the line of a third party, that occurs at the time of the purchase.