Let $f(x)=e^{-\frac{6}{x^7}}.$ Find a simplified expression for $f^{\text{'}\text{'}}(x).$

$(A)-42e^{-\frac{6}{x^7}}(\frac{8x^7-42}{x^{16}})$

$(B)42e^{-\frac{6}{x^7}}(\frac{8x^7+42}{x^{18}})$

$(C)-40e^{-\frac{6}{x^7}}(\frac{10x^7-42}{x^{16}})$

$(D)-45e^{-\frac{6}{x^7}}(\frac{10x^7-42}{x^{18}})$

$(E)40e^{-\frac{6}{x^7}}(\frac{9x^7+44}{x^{16}})$

$(F)42e^{-\frac{6}{x^7}}(\frac{9x^7+44}{x^{18}})$

$(G)40e^{-\frac{6}{x^7}}(\frac{8x^7+42}{x^{16}})$

$(H)-42e^{-\frac{6}{x^7}}(\frac{8x^7-42}{x^{18}})$