\textbf{156 --} Which of the following statements is correct?
\textbf{A --} In $\beta^-$ decay, the emitted electron did not exist inside the nucleus, and furthermore it is not one of the atomic orbital electrons.
\textbf{B --} In $\beta^+$ decay, the emitted particle from the nucleus has the same mass as the electron.
\textbf{C --} Most nuclei after $\beta$ decay remain in a stable state.
\textbf{D --} In $\beta^+$ decay, one of the neutrons inside the nucleus is converted into a proton and a positron.
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(1) A and B \hspace{1cm} (2) A and C \hspace{1cm} (3) B and D \hspace{1cm} (4) B and C
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