$120.$ The Shell $($or the command interpreter$)$ is the:

A$.$ File management layer

B$.$ User interface layer

C$.$ Kernel $($process manager$)$

D$.$ Memory management layer

$121.$ An application developer consider OS is:

A$.$ A set of facilities

B$.$ A set of services

C$.$ A set of forms

D$.$ A set of system calls

$122.$ The following OS service was designed as a special service:

A$.$ User interface

B$.$ Accounting

C$.$ program execution

D$.$ File$-$system manipulation

$123.$ When one process is in critical section:

A$.$ other processes may be in its critical section

B$.$ Other processes must no ask permission to enter its critical section

C$.$ no other process may be in its critical section

D$.$ may not follow critical section with exit section

$124.$ Processes can execute in:

A$.$ one way: concurrently

B$.$ two ways: concurrently or in parallel

C$.$ three ways: concurrently or in parallel or in hybrid way

D$.$ four ways: concurrently or in parallel or in hybrid way or in mixture way

$125.$ Management of memory needs this type of register:

A$.$ Information register

B$.$ Base register

C$.$ Border register

D$.$ Moving register

$126.$ The most suitable locking operation for several concurrent readers$($process$)$ is:

A$.$ Lock

B$.$ Exclusive lock

C$.$ Writer lock

D$.$ Shared lock

$127.$ An executable file is not a file:

A$.$ Having the exe extension

B$.$ Having a com extension

C$.$ Containing no linked code

D$.$ Ready to be executed

$128.$ Swapping uses this system call:

A$.$ swap into

B$.$ swap out

C$.$ Roll into

D$.$ Switch in