In spontaneous nuclear reaction $a\mathit{+}b\mathit{\to }c\mathit{,}$ masses of $a\mathit{,}\mathit{ }b\mathit{,}\mathit{ }c$ are $m_{\mathit{a}}\mathit{,}\mathit{ }{m}_{\mathit{b}}\mathit{,}\mathit{ }{m}_{\mathit{c}}$ respectively, then which of the following is true?

Consider the following statements

A. Spectrum of energy of $\alpha$-particles in $\alpha$-decay is line spectrum
B. Spectrum of energy of $\beta$-particles in $\beta$-decay is continuous spectrum
Which of the following option is correct?

When an ${\mathrm{U}}^{238}$ nucleus originally at rest, decays by emitting an alpha particle having speed $u$, the recoil speed of the residual nucleus is