$1$

Many users do not know which operating system they have on their computer, and are not

even sure why they need one.

Give TWO reasons why an operating system is needed on a computer. $(2)$

$4\mathrm{.}4$ Menu options sometimes have one of their letters underlined, such as Format.

$4\mathrm{.}4\mathrm{.}1$ Give ONE reason for this feature. $(1)$

$4\mathrm{.}4\mathrm{.}2$ Explain how this feature can be used, with specific reference to the above

example, i$.$e$.$ Format. $(1)$

$4\mathrm{.}5$ Consider the following screenshot of two sets of Windows controls: