The conversation between human and AI assistant.
[|Human|] Classify the following sentence into an iOS accessibility feature from the following list: Speech Synthesis, Visual Analysis, Hearing Aid Compatibility, Physical Sensors. Output should be one of the four corresponding numbers.
[|AI|] 1. Speech Synthesis
[|Human|] 
Classify the following sentence into an iOS accessibility feature from the following list: Speech Synthesis, Visual Analysis, Hearing Aid Compatibility, Physical Sensors. Output should be one of the four corresponding numbers.