Final answer:
When "a" and "i" appear together in a syllable, they usually represent the same sound as the "a" in case (Option C).
Step-by-step explanation:
When "a" and "i" appear together in a syllable, they usually represent the same sound as the "a" in case (Option C). This is because when the letters "a" and "i" appear together, they create a digraph, which represents a specific sound. In this case, the digraph "ai" is pronounced as the "a" in case.