Write the Expression as a Single Logarithm with Coefficient 1 $a \neq 1 \text { and } b \neq 1$

Multiple Choice

Write the expression as a single logarithm with coefficient 1. Assume all variables represent positive real numbers with $a \neq 1 \text { and } b \neq 1$ .
- $\log _ { 3 } m + \log 3 n$

A) $\log _ { 3 } \mathrm { mn }$
B) $\log _ { 3 } ( m + n )$
C) $\log _ { 3 } m \cdot \log _ { 3 } n$
D) $\log _ { 3 } \left( \frac { \mathrm { m } } { \mathrm { n } } \right)$