A secondary amine is

• A

  a compound with two carbon atoms and an $\mathrm{NH}_2$ group
• B

  a compound with an $\mathrm{NH}_2$ group on the carbon atom in number 2 position
• Correct answer
  C

  a compound in which 2 of the hydrogen of $\mathrm{NH}_3$ have been replaced by organic group
• D

  an organic compound with two $\mathrm{NH}_2$ groups

Solution

A secondary amine is a compound in which 2 of the hydrogen of $\mathrm{NH}_3$ have been replaced by organic group.

Hence, the correct answer is option: 'C'.