With respect to the filing of an individual income tax return, which of the following statements is correct?

1. An individual is required to file an income tax return if their only source of income is business income, even if no tax is payable.
2. An individual is required to file an income tax return if they have reached the age of 18 by the end of the year.
3. If an individual has disposed of a capital property during the year, they are required to file an income tax return, even if no tax is payable.
4. An individual is not required to file an income tax return if no tax is payable for the year.