Introduction:
Parliamentary Committees are an integral part of the Indian Parliament. They are responsible for conducting detailed examinations and investigations on various issues related to legislation, policy implementation, and government functioning. These committees play a crucial role in scrutinizing the work of the government and ensuring transparency and accountability.

Explanation:
Among the options provided, the "Demands for Grants Committee" is not a Parliamentary Committee. Let's understand why:

1. Committee on Public Accounts:
- This committee is one of the oldest and most important Parliamentary Committees.
- It examines the audit reports of the Comptroller and Auditor General (CAG) and ensures the proper utilization of public funds.
- It scrutinizes the financial transactions of the government, both revenue and expenditure, and assesses the economy, efficiency, and effectiveness of government spending.

2. Committee on Public Undertakings:
- This committee examines the reports and accounts of public sector undertakings (PSUs) and evaluates their performance.
- It ensures that these PSUs are functioning efficiently, effectively, and in accordance with the objectives laid down by the government.
- The committee also examines issues related to disinvestment, privatization, and restructuring of PSUs.

3. Committee on Estimates:
- This committee examines the estimates of revenue and expenditure of the government.
- It assesses whether the funds allocated are being utilized effectively and efficiently.
- The committee also evaluates the performance of various government schemes and programs and suggests measures for improvement.

4. Demands for Grants Committee:
- This committee is not a Parliamentary Committee.
- However, it is a crucial part of the budgetary process.
- The Demands for Grants Committee examines the demands for grants presented by various ministries and departments.
- It scrutinizes the budgetary allocations and expenditures proposed by the government and makes recommendations regarding the same.

Conclusion:
In conclusion, the "Demands for Grants Committee" is not a Parliamentary Committee. However, it plays a significant role in the budgetary process by examining the demands for grants and making recommendations. The other three options mentioned in the question (Committee on Public Accounts, Committee on Public Undertakings, and Committee on Estimates) are all important Parliamentary Committees that perform specific functions related to financial scrutiny, performance evaluation, and policy analysis.