Solve the exponential equation. Write the exact answer with natural logarithers and then approximale the result correct to three decrivel places

${10}^{5k3}=21$

Select the correct chorce below and, A necessary, fill in the arrwer boxes to complete your choice

A$.$ The exact answer$($s$)$ with nalural logarithms is are $x=$

$($Type an exact answer in simplifed form. Type an integer or a fraction. Use a comma to separate answers as needed$)$

The approximate answer$($s$)$ is$/$are $...$

$($Simplify your answer. Type an integer or a decimal. Round to three decimal places as needed. Use a comma to separate answers as needed$)$

B$.$ There is no solution. The solution set is the empty set, $6$