Respuesta :
A subject tree is a website that uses subject classifications to try to categorize Web pages. Subject trees, like the subject catalog in a library, include active linkages to the documents they index.
Thus we can match the tiles with pairs as:
1 D
2 C
3 B
4 A
What exactly is a cluster?
A cluster is a collection of interconnected computers or hosts that application of the principle and middleware (e.g. databases). Each computer in a cluster is alluded to as a "node."
Unlike grid computers, which assign each node a different work, computer clusters provide each node the very same duty.
For more information about the cluster refer to the link:
https://brainly.com/question/21629332
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