Answer: PC servers
Explanation: PC(Personal computer) servers are the helps in the utilization of the network services to the software and hardware of the computer. It manages the network resources . In the past time ,Mindrange computers, mini computers etc are present time's PC servers.
Other options are incorrect because laptops ,PDA(Personal digital assistant) or tablets are the modern version of the computer units that are portable and compact with fast processing. Thus the correct option is option PC servers.