What does the preprocessor do$?$

Question $9$Select one:

a$.$

converts the $($human$-$readable$)$ source code into $($cpu$-$readable$)$ object code

b$.$

modifies the source file as per the preprocessor directives $($file includes, macro expansions, etc..$)$

c$.$

combines object code from object files and libraries into an executable

d$.$

loads the executable program into memory for execution