As a result of radioactive decay a ${ }_{92}{\mathrm{U}}^{238}$ nucleus is changed to a ${ }_{91}{\mathrm{U}}^{234}$ nucleus. Which particles are emitted in the decay?

• A

  One proton and two neutrons

• B

  One $\alpha -$particle and one $\beta -$particle

• C

  Two $\beta -$particles and one neutron

• D

  Two ${\beta }^{+}-$particles and one proton