Which of the following Wireshark filters can a network administrator use to view the packets...

In Wireshark, a TCP Null Scan can be detected by setting a filter to show packets where no TCP flags are set. This is because a TCP Null Scan is characterized by sending TCP packets with no flags set in an attempt to identify open ports on the target system. The correct filter to use in Wireshark to detect such packets is TCP.flags==0x000, which will display only those packets where all flags are unset.

References: The information provided here is consistent with standard network security practices for detecting TCP Null Scans using Wireshark, as described in various educational resources on network security and penetration testing1.