A logic circuit provides the output $Y$ as per the following truth table: The expression for the output $Y$ is:

Let's analyze the relationship between inputs $A,B$ and output $Y$:When $B=0$, $Y=1$ (regardless of $A$).When $B=1$, $Y=0$ (regardless of $A$).This pattern shows that the output $Y$ is independent of $A$ and is simply the complement of $B$.
$$Y=\bar{B}$$
Looking at the options, $\bar{B}$ corresponds to option (3).