Answer:
the disk drive
Step-by-step explanation:
A bottle neck in a network is the condition through which the data flows becomes limited by the network of the computer system. It occurs in the user network or within the servers where there are contention for any internal server resources.
In the context, a system that consumes 0.4 seconds for the processor time and time 0.3 seconds for accessing the network. The system also takes 0.5 seconds for accessing disk drive for executing the task. So the bottle neck in this system is the disk drive.