Given the question: Information:  - Exmouth is a port town, civil parish and seaside resort in East Devon, England, sited on the east bank of the mouth of the River Exe. In 2011, it had a population of 34,432 making Exmouth the 5th most populous settlement in Devon.  - England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west. The Irish Sea lies northwest of England and the Celtic Sea lies to the southwest. England is separated from continental Europe by the North Sea to the east and the English Channel to the south. The country covers five-eighths of the island of Great Britain (which lies in the North Atlantic) in its centre and south; and includes over 100 smaller islands such as the Isles of Scilly, and the Isle of Wight.  - The River Sid is a minor river in East Devon . It flows for 10.5 kilometres southwards from a source in Crowpits Covert ( OSGB36 Grid reference SY138963 ) at a height of 206 metres above sea level . The source is at the head of a goyle or small ravine . The underlying geology is impermeable silty mudstones and sandstones of the Triassic Keuper marl , overlain with permeable Greensand and clay - with - flints . The junction between the Greensand and Keuper Marl forms a spring line . The river flows through Sidbury and Sidford to Sidmouth and is fed by springs flowing from East Hill and water from the Roncombe Stream , the Snod Brook and the Woolbrook . In Sidmouth the river outflows at the Ham through a shingle bar . The Sid Vale Association , the first Civic Society in Britain ( founded in 1846 ) is based in the Sid Vale .  - Devon (archaically known as Devonshire) is a county of England, reaching from the Bristol Channel in the north to the English Channel in the south. It is part of South West England, bounded by Cornwall to the west, Somerset to the northeast, and Dorset to the east. The City of Exeter is the county town; seven other districts of East Devon, Mid Devon, North Devon, South Hams, Teignbridge, Torridge, and West Devon are under the jurisdiction of Devon County Council; Plymouth and Torbay are each a part of Devon but administered as unitary authorities. Combined as a ceremonial county, Devon's area is and its population is about 1.1 million.  - East Devon is a local government district in Devon, England. Its council is based in Sidmouth, and the largest town is Exmouth.  - Sidmouth is a town situated on the English Channel coast in Devon, South West England, east of Exeter. In 2004, it had a population of about 15,000, of whom 40% were aged 65 or over. By the time of the 2011 census the population was 12,569. It is a tourist resort and a gateway to the Jurassic Coast World Heritage Site. A large part of the town has been designated a conservation area.    'river sid' is related to which object entity through the relation of 'mouth of the watercourse'?  Choices: - bristol channel  - celtic sea  - english channel  - river exe  - sea
The answer is:
english channel