This question is built on drawn structures, so the options cannot be reproduced as text. The chemistry it tests is set out below.

A primary amine adjacent to a hydroxyl group, treated with nitrous acid (HONO), undergoes the Tiffeneau-Demjanov rearrangement — a ring-expansion reaction.

The sequence is worth following because every step is forced. HONO first converts the primary amine into a diazonium salt. Molecular nitrogen is an outstanding leaving group, so it departs immediately and irreversibly, generating a primary carbocation — an intermediate far too unstable to survive.

Relief comes from a 1,2-alkyl shift: a carbon-carbon bond of the adjacent ring migrates to the electron-deficient centre. Because the migrating bond comes from the ring itself, the ring expands by one carbon, and the positive charge moves onto the carbon bearing the hydroxyl group.

That new cation is stabilised as an oxocarbenium ion, and simply losing a proton from oxygen delivers a ketone in the expanded ring.

So the transformation converts an amino alcohol on an n-membered ring into a ketone on an (n+1)-membered ring — which is why the method is valued for making medium-sized rings that are otherwise hard to build.

Options showing the ring unchanged, or a simple substitution of NH₂ by OH, miss the rearrangement that is the whole point of the reaction.

Per the official final answer key the answer is option (B).