If $a-1=b+2=c-3=d+4$, which of the four quantities $a,b,c,d$ is the largest?
$\textbf{(A)}\ a \qquad \textbf{(B)}\ b \qquad \textbf{(C)}\ c \qquad \textbf{(D)}\ d \qquad \textbf{(E)}\ \text{no one is always largest}$
We have $a = a$, $b = a - 3$, $c = a + 2$, and $d = a - 5$, so now as $2 > 0 > -3 > -5$, $c$ is always largest. Hence the answer is $\boxed{\text{C}}$.