The correct option is (c).
Explanation
The Universe represents the totality of all matter, energy, and space. Its structure is hierarchical, where stars aggregate to form galaxies, and galaxies aggregate to form the Universe.Statement 1 is Incorrect: A huge system or cluster of millions (or billions) of stars, clouds of dust, and gases is technically defined as a Galaxy (such as the Milky Way). The Universe is not a single cluster of stars but the container for all such clusters.
Statement 2 is Correct: The Universe is constituted by millions of galaxies. These galaxies are the primary massive structures that populate the vastness of space.
Statement 3 is Correct: The Universe is infinite or near-infinite in scale, and it is constantly expanding. Consequently, its exact size is unknown, making it difficult to imagine its true magnitude.
Key Takeaway: There is a distinct hierarchy in celestial organization: a Galaxy is a group of stars, while the Universe is the collection of millions of galaxies.