Write the Exponential Equation in Logarithmic Form $81 ^ { 1 / 2 } = 9$

Multiple Choice

Write the exponential equation in logarithmic form. $81 ^ { 1 / 2 } = 9$

A) $\log _ { 81 } 9 = \frac { 1 } { 2 }$
B) $\log _ { 81 } \frac { 1 } { 2 } = 9$
C) $\log _ { 81 } 9 = 2$
D) $\log _ { 81 } 9 = - \frac { 1 } { 2 }$
E) $\log _ { 9 } 81 = \frac { 1 } { 2 }$