A group of students is working on a puzzle. Each student has two pieces necessary to complete it. All the students want to complete it. This is an example of a(n) ________________

The adrenal glands are important in your body's reaction to ______

a. stress c. digestion b. sleep d. pleasurable fantasy

At about 12 months of age, infants ______

a. begin cooing c. say their first word b. begin babbling d. begin using intonation