Final answer:
DNS enumeration is most likely to produce the needed information when trying to discover the name of an IT administrator in a passive vulnerability assessment.
Step-by-step explanation:
The student's question involves information security and specifically the process of conducting a passive vulnerability assessment in a corporate environment. In the context of this task, the consultant is trying to find out the name of one of the IT administrators, which is generally considered a piece of private information. Among the options provided, B. DNS enumeration is MOST likely to yield the needed information. DNS enumeration can uncover a range of information, such as the names of servers, and sometimes the naming conventions can reveal the names of IT staff who have accounts on these servers. It may also reveal email addresses, which often include full names and can be particularly useful in identifying IT administrators.