The expression $\sqrt{13+\sqrt{7+\sqrt{4}}}$ is equal to
(A) 7
(B) 8
(C) 6
(D) 4
(E) 5
We evaluate from the inside towards the outside:

$$
\sqrt{13+\sqrt{7+\sqrt{4}}}=\sqrt{13+\sqrt{7+2}}=\sqrt{13+\sqrt{9}}=\sqrt{13+3}=\sqrt{16}=4
$$

ANSwER: (D)