To obtain 3-methylbutan-2-ol from acetaldehyde, the Grignard's reagent used is

Which of the following aldehyde has buttery odour?

Identify product B in following reaction.

Propanone $$\xrightarrow{\mathrm{Ba}(\mathrm{OH})_2} \mathrm{~A} \xrightarrow[-\mathrm{H}_2 \mathrm{O}]{\Delta} \mathrm{B}$$

Identify compound A from following reaction.

$$\mathrm{A}+\mathrm{C}_2 \mathrm{H}_5 \mathrm{MgBr} \xrightarrow[\text { ety }]{\text { drer }} \mathrm{B} \xrightarrow{\mathrm{H}_3 \mathrm{O}^{+}} \text {3-methylpentan-3-ol }$$