What is the fundamental distinction between 'internal fragmentation' and 'external fragmentation' in memory management?

Internal fragmentation occurs when a fixed-size memory block allocated to a process is larger than what the process actually needs, wasting the unused space inside that already-allocated block. External fragmentation instead occurs when free memory becomes broken up into many small, scattered chunks over time (as processes are allocated and freed), such that the total free memory may be sufficient for a new request, but no single contiguous chunk is large enough to satisfy it. Internal fragmentation is commonly associated with fixed-size paging, while external fragmentation is more associated with variable-sized allocation like segmentation, but neither is exclusively confined to one or the other in the absolute way option A claims, and options C, D, and E describe unrelated or inaccurate distinctions.