gwd27 Q12

Which of the following, if true, would most clearly undermine the possible explanation for the whirling gas in M87 that is mentioned in the last sentence of the first paragraph?

1. The stars in a star cluster at the center of M87 could exert a strong gravitational force without tearing the cluster apart.

2. A cluster of stars at the center would preclude the existence of certain other astronomical phenomena that have been observed at the center of M87.

3. The stars within many existing galaxies, such as NGC 4258, are more closely spaced than are the stars within the core of M87.

4. Only one other galaxy has been observed to contain gas clouds whirling about its center as they do about the core of M87.

5. The gravitational force of a cluster of a billion or so dim stars would be sufficient to cause a whirling ring of gas and dust to collect around the center of a galaxy.

Answer: A

why here is "without tearing the cluster apart."?