What Is the Conjugate Acid O $\mathrm { NH } _ { 3 }$

What is the conjugate acid o $\mathrm { NH } _ { 3 }$ ?

A) $+ \mathrm { NH } _ { 3 }$
B) $\text { -NH }$
C) ${ } ^ { + } \mathrm { NH } _ { 4 }$
D) $- \mathrm { NH } _ { 2 }$
E) $+ \mathrm { NH } _ { 2 }$