Cadet Competition Written Practice Exam 2025 - Free Practice Questions and Study Resources.

The correct answer is the universe, which encompasses all known matter, energy, planets, stars, galaxies, and even the fundamental forces that govern them. It includes everything from the smallest subatomic particles to the largest galaxies and cosmic structures. By defining the universe in this way, it highlights how it contains all celestial bodies, including stars, planets, and galaxies, as well as biological entities such as animals, plants, and humans.

The Milky Way refers specifically to our galaxy, which is just one of billions of such systems comprising the universe, and thus does not include the entirety of existence. The solar system is a collection of planets and celestial bodies that orbit our Sun, limited to that particular region of space. The cosmos is often used interchangeably with the universe, but it can sometimes be more philosophical in context, leading to potential ambiguity about the exact scope it references. In contrast, the universe is a precise term that clearly encapsulates everything.