Which of the following compounds undergoes maximum hydration?

$A$ compound $A$ with molecular formula $C_{10}H_{13}Cl$ gives a white precipitate on adding silver nitrate solution. $A$ on reacting with alcoholic $KOH$ gives compound $B$ as the main product. $B$ on ozonolysis gives $C$ and $D$. $C$ gives Cannizzaro reaction but not aldol condensation. $D$ gives aldol condensation but not Cannizzaro reaction. $A$ is:

Which of the following is a lachrymatory agent or tear gas?

Reduction of which compound gives an optically active alcohol?

Aldol condensation reaction is

The formation of cyanohydrin from a ketone is an example of