Rewrite the Logarithm as a Ratio of Natural Logarithms $\ln \frac { x } { 3.1 }$

Multiple Choice

Rewrite the logarithm as a ratio of natural logarithms. ?
Log_3.1 x
?

A) $\ln \frac { x } { 3.1 }$
B) $\ln 3.1 x$
C) $\frac { \ln 3.1 } { \ln x }$
D) $\frac { \ln x } { \ln 3.1 }$
E) None of these