Ans: B
$\begin{array}{cl}
& 1011001011001011_2 \\
= & 2^{15}+2^{13}+2^{12}+2^9+2^7+2^6+2^3+2+1\\
= & 2^{3+12}+2^{1+12}+2^{12}+2^{3+6}+2^{1+6}+2^6+8+2+1 \\
= & (2^3+2+1)\times 2^{12}+(2^3+2+1)\times 2^6+11\\
= & 11 \times 2^{12}+11\times2^6+11
\end{array}$
