According to Piaget, Which Statement Is True Regarding Stages of Thinking

According to Piaget, which statement is true regarding stages of thinking?

A) Sensorimotor and preoperational thinking must be completed before the concrete operational stage, but not before formal operational thinking.
B) Sensorimotor and preoperational thinking must be completed before the formal operational stage, but not before concrete operational thinking.
C) Thinking alternates between stages throughout development.
D) All stages must be accomplished in the correct order.