Answer from cs61c-al (Phillip Chin 16156822) for Question 1
The C preprocessor essentially processes the file before compiling and takes care of the macros and constants. It would then make sense that the input language is C. The output would also be C, because it is done just before compiling where it still exists as uncompiled C code. In the figure, the preprocessor would be located under C program and above Compiler.