Which of the following highly uses the concept of an array?

Spatial locality is the memory-access principle that when one memory address is accessed, addresses physically close to it are highly likely to be accessed soon after. A structure exhibits this property to the extent that it packs its elements into contiguous memory locations, since visiting one element then naturally lands near the next.

• Binary search tree: each node is allocated wherever the heap has free space and is linked only through left/right child pointers, so traversing it jumps between scattered addresses rather than contiguous ones.

• Scheduling of processes: the scheduler's defining structure is a queue that orders processes by arrival time or priority; that ordering discipline -- not contiguous memory layout -- is what characterizes scheduling.

• Spatial locality: an array stores every element at consecutive addresses, so stepping through indices i, i+1, i+2 accesses adjacent memory directly -- the textbook case of this principle.

• More than one of the above: would require at least two listed items to independently store elements in contiguous memory; only one does.

• None of the above: would require that no listed item satisfies the contiguous-memory test; one clearly does.

Cross-check: CPU caches fetch a whole cache line -- a contiguous block of memory -- on every miss, so an access pattern is best exploited when the underlying storage is itself laid out contiguously. Among the options here, that is precisely the array's default behaviour: unlike a pointer-linked binary search tree or a queue-based scheduler (neither of which need keep their elements together in memory), an array's very definition guarantees contiguous storage.

Therefore, the concept that highly uses the array is spatial locality.