Correct option is A
Option (A) is the correct order of the given sentences: D, B, C, A
Explanation of the sequence:
D introduces the subject: “The Arthashastra is”
B gives its importance: “one of the world’s earliest books”
C tells the subject: “devoted to statecraft”
A ends with how it is written: “in unadorned Sanskrit prose”
Bullet points:
Start with subject (D)
Describe identity (B)
Mention theme (C)
Conclude with style (A)