Files that are related to input/output and are used to model serial I/O devices such as terminals, printers and networks are called :
(A) regular files (B) character special files
(C) directories (D) block special files
D . Block Special Files
http://www.cs.wichita.edu/~chang/lecture/cs540/homework/hwk4-sol.txt
https://en.wikipedia.org/wiki/Device_file