Which of the following reactants,on reaction with concentrated $NaOH$ followed by acidification,gives the following lactone as the product?

Hex$-4-$en$-2-$ol on treatment with $PCC$ gives $'A'.$ $'A'$ on reaction with sodium hypoiodite gives $'B',$ which on further heating with soda lime gives $'C'.$ The compound $'C'$ is $....... .$

The reaction that does not give benzoic acid as the major product is

In the reaction sequence: $CH_2OH-CHOH-CH_2OH$ $\xrightarrow{KHSO_4/\Delta} (X)$ $\xrightarrow{(C_2H_5O)_3Al/\Delta} (Y)$,$(Y)$ will be:

What are $A, B, C$ and $D$ in the following cross-aldol condensation reaction?
$\text{Propanal} + \text{Ethanal} \xrightarrow[ii) \ \Delta]{i) \ NaOH} A + B + C + D$
(The products are the four possible $\alpha,\beta$-unsaturated aldehydes formed by self and cross-aldol condensation followed by dehydration.)

Find the end product of the following reaction:
Product is