The correct answer is option 2: Mitochondrion.

Mitochondria are double-membraned organelles found in eukaryotic cells. They are often referred to as the "powerhouses" of the cell because they are responsible for producing energy in the form of ATP through cellular respiration.

One key feature of mitochondria is that they contain their own DNA, known as mitochondrial DNA (mtDNA). This DNA is separate from the nuclear DNA found in the cell`s nucleus.

The presence of mtDNA in mitochondria is believed to be the result of endosymbiosis, a theory that suggests mitochondria were once free-living prokaryotes that were engulfed by a larger eukaryotic cell. Over time, the prokaryotic cell became a symbiotic organelle within the eukaryotic cell, retaining its own DNA.

This unique characteristic of mitochondria allows them to reproduce independently of the cell`s nucleus and plays a crucial role in various cellular functions, including energy production and regulation.

Therefore, the correct answer is option 2: Mitochondrion.