9. Four numbers $a, b, c, d$ are such that $a+5=b^{2}-1=c^{2}+3=d-4$. Which of them is the largest?
A $a$
B $b$
C $c$
D $d$
$\mathrm{E}$ more information required
9. D Note that $d=c^{2}+7$, so $d>c ; d=b^{2}+3$, so $d>b$; and $d=a+9$, so $d>a$. Hence $d$ is the largest.