The integral $\int_{0}^{1} \frac{1}{7^{\left[\frac{1}{x}\right]}} dx$, where $[\,.\,]$ denotes the greatest integer function, is equal to
\( 1 + 6 \log_{e}\!\left(\frac{6}{7}\right) \)
\( 1 - 6 \log_{e}\!\left(\frac{6}{7}\right) \)
\( \log_{e}\!\left(\frac{7}{6}\right) \)
\( 1 - 7 \log_{e}\!\left(\frac{6}{7}\right) \)