Which among the following compounds is a hemiacetal?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$:
Assertion $A$: Acetal/Ketal is stable in basic medium.
Reason $R$: The high leaving tendency of alkoxide ion gives the stability to acetal/ketal in basic medium.
In the light of the above statements,choose the correct answer from the options given below:

Which of the following reagents can be used to distinguish between an aldehyde and a ketone?

In the given reaction,the number of chiral carbon$(s)$ in product $A$ is .......
(Where $Et$ is $-C_2H_5$)

The given reaction is an example of an intramolecular aldol condensation. Identify the product $(A)$ formed in the reaction:
$1,5-\text{cyclooctanedione} \xrightarrow{H_2SO_4, H_2O} (A)$

Identify the reactant $X$ and the product $Y$ in the reaction of acetone with a Grignard reagent followed by hydrolysis.