If \({\rm{f}}\left( {\rm{x}} \right) = \sqrt {25 - {{\rm{x}}^2}} {\rm{\;}},{\rm{\;}}\) then what is \(\mathop {{\rm{Lim}}}\limits_{{\rm{x}} \to 1} \frac{{{\rm{f}}\left( {\rm{x}} \right) - {\rm{f}}\left( 1 \right)}}{{{\rm{x}} - 1}}\) equal to?
1
\(\frac{1}{5}\)
2
\(\frac{1}{24}\)
3
\(\sqrt {24} \)
4
More than one of the above
5
None of the above