The major product of the following reaction is :

$\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CH}=\mathrm{O} \xrightarrow[\text { reflux }]{\substack{\text { excess } \mathrm{HCHO} \\ \text { alkali }}}$ ?

Residue (A) + HCl (dil) $\rightarrow$ Compound (B)

Structure of residue (A) and compound (B) formed respectively is :

The compounds which give positive Fehling's test are :

Choose the correct answer from the options given below :

In the above reaction product 'P' is