3. Given real numbers $a, b, c$ satisfy $2^{a}=5, 2^{b}=10, 2^{c}=80$. Then the value of the algebraic expression $2006 a-3344 b+1338 c$ is ( ).
(A) 2007
(B) 2008
(C) 2009
(D) 2010
3. B.

From $2^{b-a}=2^{b} \div 2^{a}=2^{1}$, we get
$$
b=a+1 \text {; }
$$

From $2^{c-a}=2^{c} \div 2^{a}=80 \div 5=2^{4}$, we get $c=a+4$.
Thus, $2006 a-3344 b+1338 c$
$$
\begin{array}{l}
=2006 a-3344(a+1)+1338(a+4) \\
=2008 .
\end{array}
$$