Write the given equation in exponential form.
log7 = 3

For this case we have that by definition of logarithmic properties that, the expression
[tex]log_ {b} (a) = c[/tex] is equivalent to:
[tex]b ^ c = a[/tex]
Then, we have the following expression:
[tex]log_ {7} () = - 3[/tex]
It can be equivalent to:
[tex]7 ^ {- 3} =[/tex]
Answer:
The correct option is option A
[tex]7 ^ {-3}[/tex]