Consider the single bit flip error detecting and correcting…

Consider the single bit flip error detecting and correcting circuit as shown below. (Note that, the choice of convention does not affect the answer in this problem.) Given that the error gate ‘E’ is of the form I1⊗X2⊗I3{“version”:”1.1″,”math”:”\(I_1 \otimes X_2 \otimes I_3\)”}.What is the state of the ancillary qubit A1{“version”:”1.1″,”math”:”\(A_1\)”} at the ‘Stage’ marked in red?