In which year did the Lisbon Treaty come into force?

2009

The correct answer is option 3: 2009

In 2009 the Lisbon Treaty came into force.

More about the treaty:

The Lisbon Treaty, formally known as the Treaty of Lisbon, is an international agreement that reformed the constitutional structure of the European Union (EU). It was signed on December 13, 2007, in Lisbon, Portugal, and came into force on December 1, 2009. The treaty was designed to make the EU more efficient, democratic, and capable of addressing global challenges.