Marina is a ten-year-old girl who idolizes singers like Mariah Carey and Christina Aguilera. She compares herself to them and imitates them while singing in front of her bedroom mirror. These singers are known as Marina’s: a. primary group. b. reference group. c. out-group. d. in-group.

B.) Reference Group

A reference group is the group of people that a person looks to as a point of comparison. This is in terms of attitude, looks, behavior, skill, etc.

In Marina's case, she looks up to the two singers and uses them as a reference point in terms of her singing skill and style, as well as her behavior. In doing this, they become her reference group.

Habituation.

Explanation:

Habituation refers to the psychological learning mechanism where the reaction to a stimulus is reduced after repeated exposure to it. This definition suggests that because of repeated exposure to it, an organism can tend to ignore a stimulus. It happens in everyday life but we still do not realize it to a large extent. As per the question,  Libby doesn’t feel the pencil behind her ear as she left it there and forgot about it is an example of habituation.