What is ${\left( 5^{-5} \right)^{-4}}$

${\frac{1}{625}^{ -9 }}$ ${5^{ -9 }}$ ${\frac{1}{625}^{ 20 }}$ ${\frac{1}{625}^{ \frac{1}{625} }}$ ${5^{ \frac{1}{625} }}$ ${5^{ 20 }}$