Solve the Equation and Express the Solution in Exact Form $\ln x - \ln ( x - 3 ) = \ln 7$

Multiple Choice

Solve the equation and express the solution in exact form.
- $\ln x - \ln ( x - 3 ) = \ln 7$

A) $\varnothing$
B) $\left\{ \frac { 7 } { 2 } \right\}$
C) $\{ 4 \}$
D) $\left\{ \frac { 3 \ln 7 } { \ln 7 - 1 } \right\}$