Let $f:[2,\infty)\rightarrow R$ be the function defined by $f(x)=x^2-4x+5,$ then the range of f is

Question

$$\begin{array}{1 1}(a)\;R & (b)\;[1,\infty)\\(c)\;[4,\infty) & (d)\;[5,\infty)\end{array}$$