The correct answer is: C. high intra class similarity.
A good clustering method will produce high quality clusters with high intra class similarity, which means that the data points within each cluster are similar to each other, and low inter class similarity, which means that the data points in different clusters are dissimilar to each other.
Option A is incorrect because high inter class similarity means that the data points in different clusters are similar to each other, which is not what we want in a good clustering method.
Option B is incorrect because low intra class similarity means that the data points within each cluster are dissimilar to each other, which is also not what we want in a good clustering method.
Option D is incorrect because no inter class similarity means that there are no clusters at all, which is not a good clustering method.