What do we call the federation of states formed in 1901?

• The British Empire
• The Commonwealth of Australia
  Explanation:

  "The federation of states formed in 1901 is called the Commonwealth of Australia. This federation united six British colonies—New South Wales, Victoria, Queensland, South Australia, Western Australia, and Tasmania—into a single nation on January 1, 1901."
• The United States of Australia
• The Australian Confederation