Please answer the following question: Information:  - The Baltic Sea (  ; ) is a sea of the Atlantic Ocean, enclosed by Scandinavia, Finland, the Baltic countries, and the North European Plain. It includes the Gulf of Bothnia, the Bay of Bothnia, the Gulf of Finland, the Gulf of Riga, and the Bay of Gdask. The sea stretches from 53°N to 66°N latitude and from 10°E to 30°E longitude. A mediterranean sea of the Atlantic, with limited water exchange between the two bodies, the Baltic Sea drains through the Danish islands into the Kattegat by way of the straits of Øresund, the Great Belt, and the Little Belt.  - The Gulf of Riga, Bay of Riga, or Gulf of Livonia is a bay of the Baltic Sea between Latvia and Estonia.  - An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island in a river or a lake island may be called an eyot or ait, and a small island off the coast may be called a holm. A grouping of geographically or geologically related islands is called an archipelago, e.g. the Philippines.  - Ruhnu is an Estonian island in the Gulf of Riga in the Baltic Sea. It is administratively part of Saare County but is geographically closer to the Latvian mainland. At , it has currently fewer than 100, mostly ethnic Estonian, permanent inhabitants. Prior to 1944, it was for centuries populated by ethnic Swedes and traditional Swedish law was used.  - Ruhnu Airfield is an airfield on Ruhnu island in Estonia . The airfield is situated to the south of the island , near the village of Ringsu . Its ICAO airport code is EERU . It has no IATA airport code .  - Latvia, officially the Republic of Latvia, is a country in the Baltic region of Northern Europe, one of the three Baltic states. It is bordered by Estonia to the north, Lithuania to the south, Russia to the east, and Belarus to the southeast, as well as a maritime border to the west alongside Sweden. Latvia has 1,957,200 inhabitants and a territory of . The country has a temperate seasonal climate.  - Saare County, or Saaremaa, (or "Oesel") is one of 15 counties of Estonia. It consists of Saaremaa, the largest island of Estonia, and several smaller islands near it, most notably Muhu, Ruhnu, Abruka and Vilsandi. The county borders Lääne County to the east and Hiiu County to the north. In January 2013 Saare County had a population of 30,966  constituting 2.4% of the population of Estonia.    Given the paragraphs above, decide what entity has the relation 'located in the administrative territorial entity' with 'saare county'.
A:
ruhnu airfield