His book has a short but useful introduction.

A. deduction

B. end

C. termination

D. conclusion

Answer: Option D

Solution(By Examveda Team)

Introduction : the action of introducing something.
Deduction : the action of deducting or subtracting something.
End : a final part of something, especially a period of time, an activity, or a story.
Termination : the action of terminating something or the fact of being terminated.
Conclusion : the end or finish of an event, process, or text.

Antonym of Introduction is Conclusion