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A $4:1$ multiplexer is to be used for generating the output carry of a full adder. $A$ and $B$ are the bits to be added while $C_{in}$ is the input carry and $C_{out}$ is the output carry. $A$ and $B$ are to be used as the select bits with $A$ being the more significant select bit.

Which one of the following statements correctly describes the choice of signals to be connected to the inputs $I_{0},$ $I_{1},$ $I_{2}$ and $I_{3},$ so that the output is $C_{out}$?

1. $I_{0}=0, I_{1}=C_{in},I_{2}=C_{in}$ and $I_{3}=1$
2. $I_{0}=1, I_{1}=C_{in},I_{2}=C_{in}$ and $I_{3}=1$
3. $I_{0}=C_{in}, I_{1}=0,I_{2}=1$ and $I_{3}=C_{in}$
4. $I_{0}=0, I_{1}=C_{in},I_{2}=1$ and $I_{3}=C_{in}$