What is the compound $D$ in the following reaction sequence?
$CH_3CH_2OH$ $\xrightarrow{P + I_2} A$ $\xrightarrow{Mg} B$ $\xrightarrow{HCHO} C$ $\xrightarrow{H_2O} D$

The major product in the given reaction is

When wine is exposed to air,it becomes sour. The reason for this is -

Isopropyl alcohol on oxidation gives

$A$ compound $A$ on oxidation gives acetaldehyde,and further oxidation gives an acid. After the first oxidation,the product reacts with ammoniacal $AgNO_3$ to produce a silver mirror. Compound $A$ is likely to be:

Major product $A$ is