GATE General Aptitude and CS Solutions Practice Test 2026 - Free GATE Practice Questions and Study Guide

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.