The correct answer is: D. descriptive and unsupervised.
Clustering is a type of unsupervised learning. In unsupervised learning, the algorithm is not given any labels or targets to predict. Instead, it is given a set of data and must find patterns in the data on its own. Clustering is a type of unsupervised learning because it is used to find groups of data points that are similar to each other. The algorithm does not need to be told which data points belong in which group; it can find the groups on its own.
The other options are incorrect because they do not describe clustering accurately. Option A is incorrect because clustering is not predictive. It does not try to predict future values. Option B is incorrect because clustering is not supervised. It is not given any labels or targets to predict. Option C is incorrect because clustering is not descriptive. It does not try to describe the data. It tries to find groups of data points that are similar to each other.