Question

The main memory of a computer must be large enough to contain the active parts of
a The operating system.
b. The applications.
c. Input/output storage & working storage.
d. All of the above
device​

Answer 1

Correct Answer: the applications

Answer 2

d. All of the above.

The operating system is the first and foremost priority, An operating system is a software which monitors hardware, softwares, device wellbeing etc. You can't use a computer without an operating system.

next you usually use a computer to run applications, if you don't have memory to run applications then using the computer is a wastage.

Input/output and working storage is the most important since without space for working storage there is no use in utilizing the applications.

hope I helped! :D