Answer:
The answer to this question is option "d".
Explanation:
The answer is user will not be able to login at all. The user wants to log in to the salesforce by its IP address. But in the server, all the IP addresses will be registered for their special work. When the user inserting their IP address to log in to the salesforce. The first server will be checking into there database. If IP address doesn't match it will not permit to access salesforce because in their server it is not a valid IP address. It is registered in sever but not for this user.
So the answer to this question is option "d".
A pro of HCI technology is that its user friendly and a con about it is that you have to teach the user what to do or guide them!