To solve this question, the user needs to be familiar with the structure of a war file, which is a compressed file format used to package web applications.

The compiled class files are stored in the /WEB-INF/classes directory inside the war file. Therefore, the correct answer is:

The Answer is: C. /WEB-INF/classes.

Option A (/META-INF/classes) is incorrect because the META-INF directory in the war file contains metadata files, not compiled class files.

Option B (/classes) is also incorrect because there is no such directory in a typical war file.

Option D (/root/classes) is incorrect because there is no root directory in a war file.