Question: What is the expected behavior of the `CatPutByte(BYTE Data)` function in a (U)SIM API when executed normally?
Option 1: Overwrite the entire proactive command buffer with the provided byte.
Option 2: Append the provided byte to the data in the constructed proactive command buffer.
Option 3: Return an error code indicating that the buffer is full before appending the byte.
Option 4: Reset the proactive command buffer before appending the new byte.
Explanation: According to conformance requirements, `CatPutByte` should append the provided byte to the data in the constructed proactive command buffer, preserving existing data and adding the new byte, which is crucial for correctly building proactive commands without data loss.