premise: Billy has only visited Saint Kitts & Nevis, Daniel has only visited Malaysia, Bobby has only visited Federated States of Micronesia, Rodney has only visited Thailand, Tyrone has only visited Cuba, Julian has only visited Costa Rica, Larry has only visited Bolivia, Ruben has only visited Guyana, Hugh has only visited Eswatini, Ryan has only visited Democratic Republic of the Congo
hypothesis: Marvin didn't visit Guyana