Explanation:

- The Index of Industrial Production (IIP) is a key indicator that reflects the industrial activity in a country.

- It uses a base year to compare current production levels to those of a specified benchmark year.

- Option 3: 2011-2012

- The correct base year for the current all India Index of Industrial Production is 2011-2012.

- Option 1: 2005-2006

- Earlier versions of the IIP might have used this base year, but it is outdated now.

- Option 2: 2004-2005

- This is not used as the base year for the currently accepted IIP.

- Option 4: 2010-2011

- This is not the base year for the IIP as of the current accepted standard.