Explanation
let's remember this property of the exponent number
[tex]a^m\cdot a^n=a^{m+n}[/tex]Step 1
solve by applying the property. ( let the same base and add the exponents)
[tex]\begin{gathered} 6^4\cdot6^{-5} \\ 6^4\cdot6^{-5}=6^{4+(-5)} \\ 6^4\cdot6^{-5}=6^{-1} \\ \end{gathered}[/tex]hence, the answer is
[tex]d)6^{-1}[/tex]I hope this helps you