A radioactive nucleus emits an $\alpha$-particle or a $\beta$-particle, producing a product nucleus. Which decay process could have formed the product nucleus given?
- A$^{226}_{88}\text{Ra} \xrightarrow{\alpha} ^{224}_{86}\text{Rn}$
- B$^{238}_{92}\text{U} \xrightarrow{\alpha} ^{242}_{94}\text{Pu}$
- C$^{228}_{88}\text{Ra} \xrightarrow{\beta} ^{228}_{87}\text{Fr}$
- D$^{231}_{90}\text{Th} \xrightarrow{\beta} ^{231}_{91}\text{Pa}$