Mathematics

Problem

Let

f(x)=\begin{cases}2x+3,&x<1\\x^{2},&x\ge 1\end{cases}

. Which of the following lists all the critical point(s) of

f

? a)

x=1

only. b) No critical points. c)

x=0

and

x=1

. d)

x=0

only.