1.
In the following sequence of reactions:
CH3CH2OHP/Br2\text{CH}_3\text{CH}_2\text{OH} \xrightarrow{\text{P}/\text{Br}_2} A Mg/ether\xrightarrow{\text{Mg}/\text{ether}} B HCHO\xrightarrow{\text{HCHO}} C H2O\xrightarrow{\text{H}_2\text{O}} D
The compound D is: