Where is the River E to be found?

The River E is a river in the Highlands of Scotland. It begins in the north-west of the MonadhLiath Mountains, to the south-east of Loch Ness. It runs in a north-westerly direction for about 10 km, before flowing into Loch Mhòr.

The River E is among the shortest place names in the world.

The other answer choices given are places in which other single-character-named rivers are to be found.

Oregon, USA, has the River D, which is not only amongst the shortest named rivers, it vies with the Roe River in Montana as the shortest river in the world. D River flows a mere 120 feet (but only when tides are at their highest) from Devil's Lake into the ocean.

Devon, in southern England, has the River O, known also as O Brook. It is a short tributary of the West Dart River on Dartmoor, near the village of Hexworthy.

The Y River is a river in the north of Russia which flows in the territory of Arkhangelsk Oblast and the Komi Republic, roughly east from its source in Verkhnetoyemsky District. The Y flows into the Vashka River.