question_answer

If \[f(x)=\left( \frac{1+x}{1+x} \right)\] and \[g(x)=\frac{3x+{{x}^{3}}}{1+3{{x}^{2}}},\] then \[f\,\,\left( g\left( x \right) \right)\] is equal to ________.

A)  \[3f\,\left( x \right)\]

B)  \[{{[f(x)]}^{2}}\]

C)  \[f\left( 3x \right)\]                     

D)  \[-\,f\left( x \right)\]

E)  None of these