The IUPAC name of

The correct answer is Option (1) → 1-Methoxy-2-methylbut-3-en-2-ol

In IUPAC naming, –OH is the principal functional group (suffix -ol); the C=C bond is shown by -en-, and –\( \ce{OCH3} \) and –\( \ce{CH3} \) are prefixes (methoxy, methyl), cited in alphabetical order. The chain is numbered so that the carbon carrying –OH gets the lowest locant.

The compound is \( \ce{CH2=CH-C(CH3)(OH)-CH2-OCH3} \). The longest chain containing the C=C and the C–OH has four carbons (but-). Numbering from the \( \ce{CH2OCH3} \) end:

    \( \overset{4}{\ce{CH2}}=\overset{3}{\ce{CH}}-\overset{2}{\ce{C}}(\ce{CH3})(\ce{OH})-\overset{1}{\ce{CH2}}-\ce{OCH3} \)

–OH is on C-2 (from the other end it would be on C-3), the double bond starts at C-3, methyl is on C-2 and methoxy on C-1. So the name is 1-methoxy-2-methylbut-3-en-2-ol.