Parliament exercises control over public expenditure through the Comptroller and Auditor General (option 2). The Comptroller and Auditor General (CAG) is an independent constitutional authority responsible for auditing government accounts and ensuring transparency and accountability in public expenditure. The CAG also plays a crucial role in reporting on the financial management and performance of government departments and agencies. By conducting audits, the CAG helps Parliament in scrutinizing the government`s financial transactions, detecting any irregularities, and ensuring that public funds are being efficiently and effectively utilized. This control mechanism helps in maintaining fiscal discipline, preventing corruption, and promoting good governance. The other options mentioned, such as the Advocate General, Commerce Minister, and Finance Minister, do not have direct roles in the control of public expenditure.