Final answer:
Mississippi is the state that has Cat Island, Gulf Islands, and the National Seashore in the Gulf of Mexico area.
Step-by-step explanation:
The state that has Cat Island in the Gulf of Mexico, the Gulf Islands, and the National Seashore is Mississippi. Cat Island is one of several barrier islands off the coast of Mississippi near Gulfport and Biloxi. The Gulf Islands National Seashore is a park that includes natural resources located on the Gulf of Mexico coastline, including mainland areas and parts of islands in both Mississippi and Florida.