Answer:
B.O(1)
Explanation:
When we are implementing ADT stack using linked chain we can pop an entry from the stack having O(1) time complexity because in linked chain we have the head or top pointer in linked chain only.Popping and pushing in stack happens on only one end that is top.So we have move to move top in linked chain to the next and delete prev node.
The answer is multitasking. This is when the OS always programs to share resources to run at the same time.
If the applications were running on separate CPUs, then it would be multiprocessing.