The narrator is telling the story in order to explore the thoughts and feelings of several characters.
We can determine this through when the writer described that "he hoped no one would find the ball for the entire practice," and "greg couldn't wait for his turn at bat." This describes the thoughts and feelings of two different characters.
The answer could not be the other options because the readers are not learning about baseball, the narrator is not giving an opinion on the characters, and the readers are not generating an interest in baseball because they are not being taught about it.
