What country invented the Enigma Machine at the end of WWI?

What country invented the Enigma Machine at the end of WWI?

• Germany
• Russia
• Great Britain
• Austria 

EXPLANATION

The history of the Enigma starts around 1915, with the invention of the rotor-based cipher machine. As usual in history, the rotor machine was invented more or less simultaneously in different parts of the world. In 1917 there were inventions from Edward Hebern in the USA, Arvid Damm in Sweden, Hugo Koch in The Netherlands and Arthur Scherbius in German