Which one of the following reactions can be used for the preparation of $\beta$-hydroxy acid derivatives?

In the given transformation,which of the following is the most appropriate reagent?

The major product $(Z)$ of the following chemical reaction is

Predict the products of the following reactions:
$(i)$ Cyclopentanone + $NH_2OH \xrightarrow{H^+} ?$
(ii) Cyclohexanone + $2,4-DNP \xrightarrow{H^+} ?$
(iii) $R-CH=CH-CHO + NH_2CONHNH_2 \xrightarrow{H^+} ?$
(iv) Acetophenone + $CH_3CH_2NH_2 \xrightarrow{H^+} ?$

Assertion : Protonation of a carbonyl group increases its electrophilic character.
Reason : Protonation of a carbonyl group involves addition of an electrophile on nucleophilic oxygen.

Product $A$ is