A Radioactive Isotope of Atomic Number $\mathrm { Z }$ Emits an Alpha Particle, and the Daughter Nucleus Then Emits

Multiple Choice

A radioactive isotope of atomic number $\mathrm { Z }$ emits an alpha particle, and the daughter nucleus then emits a beta-minus particle. What is the atomic number of the resulting nucleus?

A) $Z - 2$
B) $Z - 3$
C) $Z + 1$
D) $Z - 1$