Programming Languages Quizzes Language Processors

Question:
Multiprogramming was made possible by

Option A):
neither input/output units that operate independently of the CPU nor operating systems
Option B):
operating systems
Option C):
input/output units that operate independently of the CPU
Option D):
both input/output units that operate independently of the CPU and operating systems

Correct Answer is Option D):
both input/output units that operate independently of the CPU and operating systems