Final answer:
Anne Sullivan was crucial to Helen Keller's development and success, as she taught her how to communicate and overcome her disabilities.
Step-by-step explanation:
Anne Sullivan was incredibly important to Helen Keller because she served as her teacher and mentor, helping her overcome the challenges of being both deaf and blind.
Sullivan taught Keller how to communicate through finger spelling and sign language, which opened up a whole new world of learning and understanding for her.
Sullivan's patience, persistence, and dedication to Keller's education were instrumental in helping her become an accomplished writer, speaker, and advocate for the rights of disabled individuals.