Which action allows Igor to dedicate five years of his design patent term to the public?

Choosing to file a disclaimer dedicating the first five years of the patent enables Igor to explicitly state that he intends to make his design patent available to the public for that period. This action effectively waives his rights to exclude others from using the design, thereby allowing public use without infringement concerns during the designated time span. The concept of filing a disclaimer is a formal mechanism that can be employed within patent law, permitting the patent holder to relinquish certain rights.

The other options do not accomplish the same goal. For instance, assigning all rights to the patent while retaining royalties would still retain ownership and the exclusive rights associated with that patent, but simply share profits with someone else. Making the patent unavailable for any licensing does not release the rights; instead, it just means that no one can legally use or benefit from the design. Requesting an extended patent term does not dedicate any part of the patent to the public—rather, it seeks additional time to enjoy exclusive rights. In summary, the action of filing a disclaimer is the only one that is specifically designed to allocate a portion of the patent term to public use.