Please choose the correct answer to the question: The Milky Way is a part of 30 or more galaxies called the Local Group. Which would be the most likely reason these galaxies are considered to be part of the Local Group?

Answer1: They are all the same type of galaxy. Answer2: They all have the same number of stars. Answer3: They are all attracted to each other by gravity. Answer4: They can all be seen without the aid of a telescope.

Answer format: answer1/answer2/answer3/answer4