设曲线为y=((x-1))^2((x-3))^2，则其极值点个数为（ ）A.2B.3C.1D.0

设曲线为$y={(x-1)}^{2}{(x-3)}^{2}$，则其极值点个数为（   ）

A.2

B.3

C.1

D.0