Concept:
The Estimates Committee examines government expenditure estimates and suggests ways to reduce wasteful spending.
• Checks economy in administration.
• Suggests improvements in efficiency.
• Examines budget estimates.
Step 1: Understand what extravagance means.
Extravagance means:
Excessive or wasteful expenditure
Step 2: Identify the committee responsible.
The committee that checks unnecessary spending is:
Estimates Committee
Step 3: Differentiate from other committees.
• Estimates Committee -- checks future expenditure
• Public Accounts Committee -- checks past expenditure
• Public Undertakings Committee -- examines PSUs
Step 4: Final conclusion.
Hence, the correct answer is:
\[
\boxed{\text{Estimates Committee}}
\]