Regarding the file filtering technology in the USG6000 product, which of the following options is wrong?

Regarding the file filtering technology in the USG6000 product, which of the following options is wrong?
A . It can identify the application that carries the file, the file transfer direction, the file type and the file extension.
B. Even if the file type is modified, it can also identify the true type of the file
C. It can identify the type of files transmitted by itself, and can block, alert and announce specific types of files.
D. It supports filtering the contents of compressed files after decompression. "

Answer: C