(A) $1.$ $\text{Hex-3-ynal}$ $(CH_3-CH_2-C \equiv C-CH_2-CHO)$ reacts with $NaBH_4$ to reduce the aldehyde to a primary alcohol $(CH_3-CH_2-C \equiv C-CH_2-CH_2OH)$,followed by $PBr_3$ to convert the alcohol to a bromide. Thus,$I$ is $CH_3-CH_2-C \equiv C-CH_2-CH_2Br$,which corresponds to structure $(D)$.
$2.$ The Grignard reagent formation from $I$ followed by reaction with $CO_2$ and acidic workup yields the carboxylic acid $J$ $(CH_3-CH_2-C \equiv C-CH_2-CH_2-COOH)$. The conversion of $J$ to the acid chloride requires $SOCl_2$ $(K)$. Thus,$J$ corresponds to structure $(B)$ and $K$ is $SOCl_2$. The pair $(J, K)$ is $(B, SOCl_2)$,which matches option $(C)$.
$3.$ The final step is the partial hydrogenation of the alkyne to a cis-alkene using Lindlar's catalyst $(H_2, Pd/BaSO_4, \text{quinoline})$. The product $L$ is a cis-alkene with an aldehyde group,which corresponds to structure $(C)$.
Therefore,the correct sequence for $(1, 2, 3)$ is $(D, C, C)$.