Explanation:

Let's evaluate all options:

(A) ✔️ Correct

• In Hadoop HDFS, the DataNode is the worker/slave node.
• It stores actual user data in the form of blocks.
• Each DataNode reports to the NameNode, which manages metadata.

(B) ❌ Incorrect

• The default block size used to be 64 MB in older Hadoop versions, and in newer versions it's 128 MB, not 32 MB.

(C) ❌ Incorrect

• The NameNode does not store actual data. It stores metadata (like filenames, block locations, permissions, etc.).

(D) ❌ Incorrect

• Since option (A) is correct, this is invalid.

✅ Final Answer: (A)