5 books are to be chosen from a lot of 10 books. If $m$ is the number of ways of choice when one specified book is always included and $n$ is the number of ways of choice when a specified book is always excluded, then which one of the following is correct?

• A

  $m \gt n$
• Correct answer
  B

  $m=n$
• C

  $m=n-1$
• D

  $m=n-2$

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