Final answer:
Helen Keller's literacy in finger spelling, her comparison to a ship in the fog, and the transformative moment of understanding language supported by Anne Sullivan are the details supporting Keller's successful communication learning.
Step-by-step explanation:
The details that best support the claim that Helen Keller learned to communicate successfully include her literacy in finger spelling, which provided her with foundational access to language. This was a significant development considering she had lost both sight and hearing after a severe illness as a child. The arrival of her teacher Anne Sullivan marks a turning point in Keller's life, separating it into two parts: before and after the introduction of language. Keller's comparison of her preliterate life to a ship lost in the fog reveals her prior mental state of isolation and her subsequent revelation, symbolizing her breakthrough in communication.
Keller's literacy narrative details the climactic moment of her understanding the connection between hand-spelled words and physical objects, which is the resolution to her earlier inability to communicate, or being in the sense of being unable to speak. The narrative demonstrates that Keller's transformation and her learning of language were largely internal processes supported by the innovative methods Sullivan employed.