【程序】 sEt tAlk oFF input “x＝” to x DoCAsE CAsE、x＞10 “ok1” CAsE、x＞20 “ok2” othErwisE “ok3” EnDCAsE sEt tAlk on rEturn

程序运行时输入x值为0，则显示结果为 ______。A．“ok1”
B．ok1
C．“ok2”
D．“ok3”