Answer:
d. The narrator is a character in the story.
Step-by-step explanation:
First person narrative form is when the events of the story are being told from the perspective of the first person, with the use of the pronouns "I, we" etc. The narrator/ speaker is also part of the story, telling the readers about the other characters from his / her own point of view.
While this form of narration enables us to fully know the character of the speaker, the readers are privy to the other characters' lives and emotions only in a limited way. They are limited to the events only within the capability of our first person narrator, limited in the accessing of the situation, allowing us to know only what the narrator tells us. And unless the other characters reveal things from their side, the readers are not capable of knowing anything.