In Australia, who must enrol to vote in federal, state, and territory elections?

• Citizens aged 18 years or over
  Explanation:

  "In Australia, all citizens aged 18 years or over must enrol to vote in federal, state, and territory elections. Enrolment is compulsory by law, ensuring that eligible citizens participate in the democratic process."
• Citizens aged 21 years or over
• Citizens working in a private sector
• Citizens working in a government sector