Which does not react with Fehling solution?

The rate of hydrate formation for the given compounds is:

What is the product of the following reaction?

Given below are two statements $:$
Statement $(I) :$ Vanillin,with the structure shown below,will react with $NaOH$ and also with Tollen's reagent.
Statement $(II) :$ Vanillin will undergo self-aldol condensation very easily.
In the light of the above statements,choose the most appropriate answer from the options given below $:$

Reduction of $>C=O$ to $CH_2$ can be carried out with:

One of the products of the following reaction is $P$. Structure of $P$ is