Question

During a negative beta decay,
(a) an atomic electron is ejected
(b) an electron which is already present within the nucleus is ejected
(c) a neutron in the nucleus decays emitting an electron
(d) a proton in the nucleus decays emitting an electron.

Answer 1

(c) a neutron in the nucleus decays emitting an electron

Negative beta decay is given as
$n\to p+e^{-}+\overline{\nu }$
Neutron decays to produce proton, electron and anti-neutrino.