Please choose the correct answer to the question: Which statement is the best description of the Milky Way galaxy?

Answer1: a collection of gases held together by inertia Answer2: a group of planets revolving around a single star Answer3: a collection of stars and gases with the Sun as its center Answer4: a group of stars, dust, and planets held together by gravity

Answer format: answer1/answer2/answer3/answer4
Answer: answer4