Explanation:

- Balance sheet audit in India is not just about checking the balance sheet; it also involves examining transactions to ensure that the financial statements are accurate.

- Annual audit refers to an audit conducted once every year, but it's a general term and not specifically synonymous with balance sheet audit.

- Continuous audit means audit activities are carried out throughout the year, not just at year-end.

- Detailed audit is a thorough review but is not specifically used for balance sheet audit in terminology.

- Statutory audit is the correct answer. It is a legally required audit of the financial statements, including the balance sheet, as per the Companies Act, 2013 in India.

Correct Answer: Option:4, Statutory audit.