Which of the Following Pairs Are Constitutional Isomers

Multiple Choice

Which of the following pairs are constitutional isomers?

A) CH₃CH=CHCH₂OH and CH₃CH=CHOCH₃
B) ClCH₂CH₂CH₂CH₃ and CH₃CH₂CH₂CH₂Cl
C) CH₃CH(OH) CH₂CH₃ and CH₃CH₂(HO) CHCH₃
D) H₂NCH₂CH=CHCOOH and HOOCCH=CH(H₂N) CH₂
E) CH₃OCH₂CH₂CH₂CH₃ and CH₃OCH₂CH₂CH₂OCH₃