What is $t^{\text{'}}(x)$ when $t(x)=7e^{x^{-8}}?$ Select the correct answer below: $t^{\text{'}}(x)=7e^{x^{-8}}{t}^{\text{'}}(x)=-56x^{-8}{e}^{x^{-8}}{t}^{\text{'}}(x)=-56x^{-9}{e}^{x^{-8}}{t}^{\text{'}}(x)=-56e^{x^{-9}}$