Who is eligible to file an International Application?

An individual eligible to file an International Application under the Patent Cooperation Treaty (PCT) includes U.S. citizens or residents. This eligibility is rooted in the PCT's framework, which allows for individuals who have a genuine and effective industrial or commercial establishment in a Contracting State, or who are nationals or residents of such a Contracting State, to submit an application.

U.S. citizens naturally fall under this category because they are nationals of the United States. However, it is also important to note that residents, which may include individuals legally residing in the U.S. even if they are not citizens, also qualify to file an International Application. This provides a wider range of applicants access to the international patent filing system compared to other choices listed, which may restrict eligibility to specific groups without considering residency status.

Considering the other options, they either limit the group of eligible applicants unnecessarily or are inconsistent with the PCT regulations, which encompass broader eligibility for residency. Thus, the inclusion of both U.S. citizens and residents in this context makes the answer accurate and representative of the eligibility criteria established by international patent laws.