What is the total number of copies of the file's metadata?

What is the total number of copies of the file’s metadata?

A storage administrator has an Isilon cluster consisting of 10 nodes with identical hardware and are members of a single node pool. A 1024Kb file stored on that cluster is protected at N+3n.

What is the total number of copies of the file’s metadata?
A . 3
B . 4
C . 6
D . 5

Answer: B