When the Radioactive Nucleus ${ } ^ { 199 } \mathrm { At }$

When the radioactive nucleus ${ } ^ { 199 } \mathrm { At }$ undergoes an alpha emission, what is the product nucleus?

A) ${ } ^ { 197 } \mathrm { Bi }$
B) ${ } ^ { 203 } \mathrm { Fr }$
C) ${ } ^ { 197 } \mathrm { Rn }$
D) ${ } ^ { 195 } \mathrm { Bi }$
E) ${ } ^ { 199 } \mathrm { Fr }$