What is the largest difference that can be formed by subtracting two numbers chosen from the set $\{ -16,-4,0,2,4,12 \}$?
$\text{(A)}\ 10 \qquad \text{(B)}\ 12 \qquad \text{(C)}\ 16 \qquad \text{(D)}\ 28 \qquad \text{(E)}\ 48$
To maximize anything of the form $a-b$, we maximize $a$ and minimize $b$.  The maximal element of the set is $12$ and the minimal element is $-16$, so the maximal difference is
\[12-(-16)=28\rightarrow \boxed{\text{D}}.\]