A neutron consists of one up (u) quark and two down (d) quarks. As the neutron decays into a proton, $\beta^-$-emission occurs. What change happens to the neutron’s quark arrangement because of the $\beta$-emission? (The symbol for a neutrino is $\nu_e$ and for an antineutrino is $\bar{\nu}_e$.)
- A$d \rightarrow u + \beta^- + \nu_e$
- B$d \rightarrow u + \beta^- + \bar{\nu}_e$
- C$u \rightarrow d + \beta^+ + \nu_e$
- D$u \rightarrow d + \beta^+ + \bar{\nu}_e$