Final answer:
The author is using a third-person limited point of view when they reveal a character's thoughts solely through dialogue.
Step-by-step explanation:
When an author informs the readers of what dwells in a character's mind only through dialogue, he is using the third-person limited point of view. In this approach, the narrator conveys the story from the perspective of one character. Readers gain insight into the character's thoughts and feelings solely based on what that character says or how they interact with others, making the perspective limited to that character. Unlike third-person omniscient narration, where the narrator knows all the characters' thoughts and actions, third-person limited narration is restricted to the perspective of a single character.