3. Given the decimal 0.123456789101112131415 $161718192021 \cdots$, the 1988th digit after the decimal point is ( ) .
(A) 0 .
(B) 3 .
(C) 4 .
( D) 8 .
(E) 9 .
3. Noting that there are 9 one-digit numbers (1 to 9), 90 two-digit numbers (10 to 99), and 900 three-digit numbers (100 to 999), and that $1988=9+90 \times 2+599 \times 3+2$;
we have
$$
\begin{array}{l}
\underbrace{0.1 \cdots 9}_{9 \uparrow} \underbrace{10 \cdots 99}_{90 \uparrow} 1 \underbrace{100 \cdots 698}_{599 \uparrow} 699 \\
\text { one-digit numbers two-digit numbers three-digit numbers } \\
\end{array}
$$

Thus, the 1988th digit is 9. Therefore, the correct choice is (E).