How many Yahoo records were compromised in the 2013 Yahoo breach according to the material?

• A. 1 million
• B. 100 million
• C. 3 billion
• D. 500 million

Answer: (C)

The material emphasizes the scale of the breach by stating that about 3 billion user accounts were compromised. This figure comes from Yahoo’s own later disclosure, which updated the earlier estimate and indicated the 2013 breach affected virtually every account Yahoo had at that time. Understanding this helps you see why the event is considered so severe: it isn’t just a small subset of users affected, but the vast majority of Yahoo’s user base, making the potential exposure of personal data—such as usernames, email addresses, birth dates, and other account details—much broader. The smaller numbers don’t fit the material because they underestimate the scope that Yahoo publicly attributed to the incident.