Let \( f \) be any continuous function on \( [0,\,2] \) and twice differentiable on \( (0,\,2) \). If \( f(0)=0 \), \( f(1)=1 \) and \( f(2)=2 \), then:
\( f''(x)>0 \) for all \( x\in(0,\,2) \)
\( f''(x)=0 \) for all \( x\in(0,\,2) \)
\( f'(x)=0 \) for some \( x\in[0,\,2] \)
\( f''(x)=0 \) for some \( x\in(0,\,2) \)