Answer:
Primacy effect
Explanation:
I will assume that the option D is "primacy effect" instead of "primary effect".
In psychology, the term "primacy effect" refers to the tendency to remember information that is presented at the start of a list better than information at the middle or end.
In this example, Kirsten was introduced to 13 people and the next day she could only recall the names of the FIRST 4 people whom she had been introduced. Out of the 13 people, she was able to remember only the information that was presented at first. Thus, this example best illustrates the primacy effect.