A: Method of passing arguments to a function that takes parameter of type reference.
for instance:
void swap( int & x, int & y )
{
int temp = x;
x = y;
y = temp;
}
int a=2, b=3;
swap( a, b );
Essentially, inside the function there won't be any copy of arguments "y" and "x" instead they refer to original variables a & b. thus no extra memory required to pass arguments and it is more efficient.