Answer:
A. Socioemotional selectivity theory.
Step-by-step explanation:
Instead of socializing with large groups of acquaintances, Nancy spends her time with a few people with whom she is emotionally close. Choosing to keep a smaller social circle is in line with the Socioemotional selectivity theory. This theory was developed by Laura Carstensen, a Stanford psychologist. This theory states that with age people become increasingly selective regarding the investment of their time and effort. Nancy chooses very well the friends with whom she spends her time.