A web page contains many small images. We can speed up the performance of the…

Concept: Multithreading lets several lightweight threads of execution run inside one process at the same time. Because those threads share the parent process's memory space, the operating system can create and switch between them at a much lower cost than creating and switching between separate processes, so a set of similar, short-lived I/O-bound tasks can overlap in time instead of each one waiting for the previous one to finish.

Application: A web page fetching many small images is the standard textbook example used to motivate this idea (Tanenbaum, Modern Operating Systems, "Threads" chapter): if the browser fetched the images strictly one at a time, each image would have to wait for the previous one's network round trip to complete before its own request could even begin, so the waiting time would add up across every image. Giving each pending image its own thread lets the browser have several of those fetches in progress together, so their network waiting time overlaps instead of stacking up in sequence, and the page finishes loading sooner — the same reasoning the textbook gives for why a browser is a natural example of a multithreaded application.

Cross-check — why this is what the question is testing, and why the other options do not fit it:

• having multiple processes: creating a separate process for each image could in principle also let fetches overlap, but a process is a heavier operating-system construct with its own private memory space, so it costs far more to create and switch between than a thread inside the same process — which is exactly why this concurrency example is built around threads, not processes.

• increasing the speed of the transmission line: this is a change to the network medium's raw bandwidth, which sits outside the browser and the web page — it is a property of the connecting infrastructure, not a technique the page or the browser itself applies; the concurrency idea this question tests is specifically about what the browser can do on its own (run multiple threads), not about upgrading the network.

• increasing the main memory of the system: more RAM changes how much data can be cached or held at once; it is not a mechanism for letting more network fetches proceed together.

So the technique this classic example is testing — and the one the browser itself applies — is running the image fetches on multiple threads.