The answer will be (C) .
Macro sometimes also called by the name unsafe function as it may evaluate its argument more than once .
Here given ,
$a=10$ , $b=11$, $c=12$.
The definition of the macro is ,
#define greater($x$,$y$) $(x)>(y)$ ? $(x) :(y)$
$c$=greater$(a++$,$++b)$
now the invocation of the macro looks like ,
$c= $($a++$)>($++b$)$ ? $($a++$) :($++b$)
so
1)first a increment to 11 .
2) b increases to 12
3) comparison occurs between them .
4) as 12 is greater that 11 so , $++b$ will be our answer.
5) due to $++b$ value of b again increases to 13 .
6) we assign value of $C=13$ .
so our required answer will be option (C) .
ref: – https://wiki.sei.cmu.edu/confluence/display/c/PRE31-C.+Avoid+side+effects+in+arguments+to+unsafe+macros
