Compounds A and C in the following reaction are:

\(\mathrm{\small{{CH}_3 {CHO} \xrightarrow[{(ii) ~H_{2}O}]{(i) ~CH_{3}MgBr}({A}) \stackrel{{H}_2 {SO}_4}{\longrightarrow}({B}) \xrightarrow[]{Hydroboration \ oxidation}(C)}}\)

1.  Identical                               

2.  Positional isomers

3.  Functional isomers       

4.  Optical isomers



Hint: A and C both are alcohols

The reactions are as follows: 

CH3CHO(ii) H2O(i) CH3MgBr CHC   |
 CH3HOH   DehydrationH2SO4, CH3C|
H=CH2
                                                   (Hydroboration Oxidation)(i) BH3(ii) H2O2/OH CH3CH2CH2OH

So structure A and C are the positional isomers because parent chain is same in both the compound but position of -OH group is different.

 CH3C|HOH and CH3CH2-CH2-OH
        CH3  


Hence, option (2) is correct.