In which year was the Mahatma Gandhi National Rural Employment Guarantee Act passed?

The correct option is 2005.

Let's break down the details of this legislative act step-by-step:
1. Introduction of the Bill: The National Rural Employment Guarantee Bill was introduced in the Parliament of India in December 2004.
2. Passing of the Act: After discussion and amendments, the bill was passed by the Parliament in August 2005 and received the Presidential assent on September 5, 2005. Thus, the Act is officially dated 2005 (National Rural Employment Guarantee Act, 2005).
3. Implementation and Renaming: The act came into force on February 2, 2006, initially in 200 districts of India. It was later renamed the "Mahatma Gandhi National Rural Employment Guarantee Act" (MGNREGA) on October 2, 2009.
4. Objective: The primary objective of the act is to guarantee at least 100 days of wage employment in a financial year to every rural household whose adult members volunteer to do unskilled manual work, thereby enhancing livelihood security in rural areas.