What is the most suitable reagent for the below mentioned conversion?

\(\mathrm{CH_{3} — CH = CH — CH_{2} — \overset{\Large{O} \\~ ||}{C}—CH_{3} \rightarrow}\)
    
\(\mathrm{CH_{3} — CH = CH — CH_{2} — \overset{\Large{O} \\~ ||}{C}—OH}\)

1.  Tollens' reagent 

2.  Benzoyl peroxide

3.  \(\mathrm I_{2}\) and NaOH solution

4.  Sn and NaOH solution

Hint: Haloform test

lodoform test is used to test presence of - COCH3 group which is converted into —COOH group.

The reaction is shown below:

 CH3CH=CHCH2CO
||CH3  (lodoform reaction)l2/NaOH solution
CH3CH=CHCH2CO
||OH + CHI3
              Pent-3-en 1-oic acid