Final answer:
An increase in arrival rate will not decrease system utilization. It will maintain or increase the load on the system as more units arrive to be processed.
Therefore, the correct answer is: option A) increase in arrival rate.
Step-by-step explanation:
System utilization is the action of using something, i.e., making practical and effective use of it. For instance, if a CPU processes transactions for a total of 40 seconds during a single minute, its utilization during that interval is 67 percent.
An increased arrival rate means that more work is coming into the system, which, unless matched or exceeded by increases in service rate or number of servers, will maintain or even increase system utilization. Hence, the option that will not lead to a decrease in system utilization is increase in arrival rate. It tends to increase system utilization, as there are more units to process.
In contrast, increasing the service rate implies that each unit is processed faster, which can lead to a decrease in the system's utilization since the system can handle more units in the same amount of time.
Similarly, an increase in the number of servers would typically decrease utilization, as more servers can process the work concurrently, reducing the load on each individual server.
Lastly, a decrease in service time means that it takes less time to handle each unit, which also decreases system utilization for the same reason as an increased service rate.