Which best describes the clusters in the data set?

number of fish in each tank at the pet store

10

11

12

13

14

15

there is only one cluster, at 10 and 11.

there is only one cluster, at 13, 14, and 15.

there are two clusters at 10 and at 11.

there are two clusters, at 10 and 11, and at 13, 14, and 15.