Xiaoming wrote a program to move a robot on a $2 \times 2$ chessboard, as shown in the figure. Each execution, the program selects one direction from ``up, down, left, right'' with equal probability for each direction, and instructs the robot to move one square in that direction. However, if the selected direction would move the robot off the board, the robot stays in place. Each execution starts from the robot's current position with a newly selected direction by the program. Assume the robot's initial position is $A$. Let $a _ { n } , b _ { n } , c _ { n }$, and $d _ { n }$ be the probabilities that the robot is at positions $A , B , C , D$ respectively after executing the program $n$ times. Select the correct options.\\
(1) $b _ { 1 } = \frac { 1 } { 4 }$\\
(2) $b _ { 2 } = \frac { 1 } { 8 }$\\
(3) $a _ { 2 } + d _ { 2 } = \frac { 3 } { 4 }$\\
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\begin{tabular}{ | l | l | }
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$A$ & $B$ \\
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$C$ & $D$ \\
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\end{tabular}
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(4) $b _ { 99 } = c _ { 99 }$\\
(5) $a _ { 100 } + d _ { 100 } > \frac { 1 } { 2 }$