Which structure allows data access only from the top, following a last-in, first-out principle?

A stack is a data structure that operates on the last-in, first-out (LIFO) principle, meaning that the most recently added item is the first one to be removed. This structure allows access only from the top, where elements can be pushed onto the stack or popped off it.

When an item is added to the stack, it sits on top of the previous items. To retrieve data, you must remove the topmost item first. This behavior is essential for various applications, such as function call management in programming languages, where the most recent function call is the first to be completed.

In comparison, a queue operates on a first-in, first-out (FIFO) principle, which is contrary to the LIFO nature of a stack. Arrays allow random access to any element, while trees are hierarchical structures that enable traversal in various ways, not limited to top access only. Thus, the stack uniquely fits the description of data access limited to the top following a last-in, first-out principle.