A graph $G$ has $m$ vertices of odd degree and ' $n$ ' vertices of even degree. Then which of the following statements is necessarily true?

• Correct answer
  A

  $m+n$ is an even number
• B

  $m+n$ is an odd number
• C

  $m+1$ is an odd number
• D

  $n+1$ is an even number

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