Calvin, who is trying to impress his psychology professor with his knowledge of infant motor development, asks why some infants learn to roll over before they lift their heads from a prone position, while others develop these skills in the opposite order. What should Calvin's professor conclude from this question?

A) Calvin clearly understands that the sequence of motor development is not the same for all infants.

B) Calvin doesn't know what he's talking about. Although some infants reach these developmental milestones ahead of others, the order is the same for all infants.

C) Calvin needs to be reminded that rolling over is an inherited reflex, not a learned skill.

D) Calvin understands an important principle: motor development is unpredictable.

Calvin's professor can conclude from his question that:

Calvin doesn't know what he's talking about. Although some infants reach these developmental milestones ahead of others, the order is the same for all infants. Option B.

Explanation:

According to "Piaget's Stage Theory of Cognitive Development" there are four stages of development in a child": sensorimotor, preoperational, concrete, and formal.

In sensorimotor stage, the infant builds an understanding of himself, interacts with the environment around him and understands how things work.

To conceptualize, he tries physical experiences of things. Then he can think abstractly ans put try to put thinks logically in the concrete stage.

Then finally by formal stage, child can make rational judgments. He or she can give reasoning for his actions. The abstract thinking is more developed. at this stage. This is same for all children. Thus, statement B is most apt from the given options.