challenge: What was the reason for Tsui's breach of COVID rules at the Witman Hung party, according to the investigation report?
  
  A. He was not wearing a mask during conversations and did not scan the LeaveHomeSafe tracing app, but also failed to provide proof of vaccination
  B. He was not wearing a mask during conversations, but scanned the LeaveHomeSafe tracing app
  C. He was not wearing a mask during conversations and did not scan the LeaveHomeSafe tracing app
  D. He scanned the LeaveHomeSafe tracing app, but did not wear a mask during conversations and failed to provide proof of vaccination
  Answer: 