issuing or assuming a stock option in a transaction to which section 424(a) applies
For purposes of this part, the term “issuing or assuming a stock option in a transaction to which section 424(a) applies” means a substitution of a new option for the old option, or an assumption of the old option, by an employer corporation, or a parent or subsidiary of such corporation, by reason of a corporate merger, consolidation, acquisition of property or stock, separation, reorganization, or liquidation, if—