If \(f(x)=\frac{x}{\sqrt{1+x^2}}\), then (fofof) (x) is

\(\frac{3 \mathrm{x}}{\sqrt{1+\mathrm{x}^2}}\)

\(\frac{\mathrm{x}}{\sqrt{1+3 \mathrm{x}^2}}\)

\(\frac{3 x}{\sqrt{1-x^2}}\)

None of these