The correct choice is (b) Inserting malware loaded USB to a system
The explanation: If a suspicious gain access to server room or into any confidential area with a malicious pen-drive loaded with malware which will get triggered automatically once inserted to USB port of any employee’s PC; such attacks come under physical hacking, because that person in gaining unauthorized physical access to any room or organization first, then managed to get an employee’s PC also, all done physically – hence breaching physical security.