3. As shown in the figure below, connect adjacent letters with horizontal "/" or vertical line segments so that these line segments form the route spelling out the word CONTEST. The number of such routes is
A. 63
B. 128
C. 129
D. 255
E. None of these
$$
\begin{array}{c}
\text { C } \\
\text { COC } \\
\text { CONOC } \\
C O N T N O C \\
C O N T E T N O C \\
C O N T E S E T N O C \\
C O N T E S T S E T N O C
\end{array}
$$
3. E All acceptable paths must end at the " $T$ " in the middle of the last row. Working backwards from " $T$ ", and considering only the left half of the grid including the middle column, there are two acceptable paths leading to the end " $T$ ": one is the horizontal path from the left $S \rightarrow T$, and the other is the vertical path from the $S$ above the top $T \rightarrow T$.
Similarly, analyzing $S, E, T, N, \cdots$, each has two paths leading to the connection of these letters. This results in $2^{6}$ acceptable paths.
Similarly, in the right half of the grid including the middle column, there are $2^{6}$ possible paths.
Since the middle column has been counted twice, there are $2^{6}+2^{6}-1$ or $2^{7}-1$ paths. Therefore, the answer is E.