J is a branched-chain alcohol with formula $\text{C}_5\text{H}_{12}\text{O}$. J is heated under reflux with excess $\text{Cr}_2\text{O}_7^{2-}/\text{H}^+$ until the reaction stops changing. An organic product K is obtained in good yield. The infra-red spectrum of K is shown. What are the structures of the branched-chain alcohol J and compound K?
- AJ: $\text{CH}_3\text{CH(CH}_3)\text{CH}_2\text{CH}_2\text{OH}$ ; K: $\text{CH}_3\text{CH(CH}_3)\text{CH}_2\text{CHO}$
- BJ: $\text{CH}_3\text{CH}_2\text{CH(OH)CH}_2\text{CH}_3$ ; K: $\text{CH}_3\text{CH}_2\text{COCH}_2\text{CH}_3$
- CJ: $\text{CH}_3\text{CH(CH}_3)\text{CH(OH)CH}_3$ ; K: $\text{CH}_3\text{CH(CH}_3)\text{COCH}_3$
- DJ: $\text{CH}_3\text{CH(CH}_3)\text{CH}_2\text{CH}_2\text{OH}$ ; K: $\text{CH}_3\text{CH(CH}_3)\text{CH}_2\text{COOH}$