A embedded system with a 20-bit logical address space and 4KB page size supports up to 64KB of physical memory. How many entries are in: A) A conventional single-level page table B) An inverted page table A) 256 , B) 16 A) 256 , B) 64 A) 64 , B) 128 A) 64 , B) 256 Contiguous memory allocation with variable memory partitions method causes one of the following problems. Internal fragmentation External fragmentation Internal and External fragmentation Wastes no space