An Yttrium Isotope Has 39 Protons and 50 Neutrons in Its

Multiple Choice

An yttrium isotope has 39 protons and 50 neutrons in its nucleus. Which one of the following symbols accurately represents this isotope?

A) ${ } _ { 39 } ^ { 50 } \mathrm { Y }$
B) ${ } _ { 50 } ^ { 89 } \mathrm { Y }$
C) ${ } _ { 50 } ^ { 39 } \mathrm { Y }$
D) ${ } _ { 89 } ^ { 39 } \mathrm { Y }$
E) ${ } _ { 39 } ^ { 89 } \mathrm { Y }$