The first function that is executed in a C program when run on the command line is main. That function returns an integer. Why?

A$.$ This value is the amount of memory that the kernel needs to free after execu$-$tion.

B$.$ This is the "exit status" of the program, accessible using $$?$ in a shell, that indicates, by convention, whether the program exited normally.

C$.$ It is an ancient C conventation that serves no specific purpose.

D$.$ This is a value that the kernel $($the operating system$)$ interprets as a boolean: if a nonzero value is returned, the kernel flags the process as "accepting," otherwise as "rejecting."

$$ Answer A$.$

$$ Answer B$.$

$$ Answer C$.$

Answer D$.$