Which statement best differentiates a stack from a heap in memory management?

• A. Stack memory supports manual deallocation, while heap is automatically reclaimed.
• B. Stack is used for static memory with LIFO discipline and automatic deallocation; heap is for dynamic memory with manual allocation/deallocation and generally slower.
• C. Stack is slower than heap in every operation.
• D. Heap memory is automatically deallocated when function returns.

Answer: (B)

The main idea is the difference in how memory is allocated and freed for two regions. The stack holds memory for function call frames and local variables in a last-in, first-out order, with automatic deallocation as functions return. This makes allocations on the stack very fast because it’s just moving the stack pointer. The heap, on the other hand, is used for dynamically allocated memory where the programmer (or runtime) requests and frees blocks explicitly, which gives flexibility in how long objects live but typically incurs more overhead and potential fragmentation, making it slower.

This is why the best statement highlights that the stack uses automatic deallocation and follows a LIFO discipline, while the heap uses manual allocation/deallocation and is generally slower.

Other options don’t fit because stack memory isn’t normally manually deallocated and heaps aren’t automatically freed when a function returns; also, stack allocations are not generally slower in every operation—their allocations are usually the fastest part of memory management.