Which of the following compounds does not undergo aldol condensation?

In the presence of a dilute base,$C_6H_5CHO$ and $CH_3CHO$ react together to give a product. The product is

Fehling solution is

$x$ is the product obtained from propanenitrile and stannous chloride in the presence of hydrochloric acid followed by hydrolysis. $y$ is the product obtained from but$-2-$ene by ozonolysis followed by hydrolysis. From the following,which product is not obtained when one mole of $x$ and one mole of $y$ react with each other in the presence of alkali followed by heating?

The carbonyl compound that does not undergo aldol condensation is

The active ion in Tollen's reagent is