D is illegal because `printf` operates on strings, not `char`s.
> 6. For each of the following items of data, specify which one of the types `char`, `short`, `int`, or `long`is the smallest one guaranteed to be large enough to store the item.
> 10. Suppose that `i` is a variable of type `int`, `j` is a variable of type `float`, and `k` is a variable of type `unsigned int`. What is the type of the expression `i + (int) j * k`?