Roger, who is 10 months old, is sitting on the floor of his room happily playing with his toys. the phone rings, and his mother leaves the room to get it. roger begins to cry. roger is experiencing:

separation anxiety

Explanation:

Separation anxiety: In abnormal psychology, the term separation anxiety is defined as an individual dealing with excessive worry or fear of getting separated from an attachment figure, loved ones, or home.

In an infant's development, the separation anxiety is considered to be as a normal phenomenon or stage, and it helps a child to understand the value of relationships and to master his or her environment.

In the question above, Roger is experiencing separation anxiety.

answer; i believe the correct answer is (4) flip a coin as each participant arrives,heads indicates assignment to the first group: tails indicates assignment to the second group;