Operating systems have been around now for over half a century. During this time, quite a variety of them have been developed. Which of the statements below are true? i the main job of the operating systems for mainframes is to provide good support to a single user ii server operating systems often run on very large personal computers, and serve multiple users at once over a network, allowing them to share resources iii sensor node operating systems run on ubiquitous systems which blend into the environment, and are oriented towards processing many jobs at once iv digital audio and multimedia systems are soft real-time systems

i and ii

i, ii, and iii

ii, iii, and iv

ii and iv