Step 1: Differentiate the candidate
Differentiate $\frac{1}{2}g(x^{2})$: $\frac{1}{2}g'(x^{2})\cdot 2x$.
Step 2: Use g' = f
Since $g'(x)=f(x)$, this becomes $x\,f(x^{2})$.
Step 3: Conclude
It matches the integrand, so the antiderivative is correct.
Final Answer:
The answer is $\frac{1}{2}g(x^{2})+c$.
\[ \boxed{\text{(C) }\dfrac{1}{2}g(x^{2})+c} \]