フリー問題

問題文

Container images are built from layers. What is the practical benefit of that structure?

選択肢

1. Each layer can be modified independently after the image has been built, so a correction can be applied to one layer without rebuilding anything above it, which is why images do not need to be versioned once they have been pushed to a registry for the first time.
2. Layers that several images have in common are stored and transferred once, so building and pulling images is faster and takes less space.
3. Layers guarantee that the container's data survives its removal, so a volume is never needed for any file that a container happens to write while it is running.
4. Layers let a container run a different kernel from the host, which makes the kernel version a property of the image rather than of the machine underneath it.