When did the Australian Constitution come into effect, uniting the colonies into one independent nation?

• {ts '1900-01-02 00:00:00'}
• {ts '1901-01-26 00:00:00'}
• {ts '1901-01-01 00:00:00'}
  Explanation:

  "The Australian Constitution came into effect on 1 January 1901, uniting the separate colonies into the Commonwealth of Australia. This marked the beginning of Australia as a federated nation."
• {ts '1910-01-01 00:00:00'}