Children who have reached the concrete operational stage are capable of ________, which is the ability to order stimuli along a quantitative dimension, such as length.

Which of the following acts as a defensive barrier against toxins and infections?

a. umbilical cord b. amniotic sac c. placenta d. amniotic fluid

________ memory is memory for general knowledge and facts about the world, as well as memory for the rules of logic that are used to deduce other facts.

A. Procedural B. Semantic C. Episodic D. Sensory