Given below are two statements :
Statement $(I) :$ $CH_3CH=CHCH_3$ and $cyclobutane$ are isomeric compounds.
Statement $(II) :$ $CH_3CH_2CH_2CH_2NH_2$ and $(CH_3CH_2)_2NH$ are functional group isomers.
In the light of the above statements,choose the correct answer from the options given below :

• A
  Both Statement $I$ and Statement $II$ are false
• B
  Both Statement $I$ and Statement $II$ are true
• C
  Statement $I$ is true but Statement $II$ is false
• D
  Statement $I$ is false but Statement $II$ is true