In ........... insertion takes place at the rear end.

Question

Accepted Answer

The correct option is (4):
A Queue is a linear data structure that operates on the First-In, First-Out (FIFO) principle, which closely mirrors a waiting line in the real world. According to this principle, the element that was inserted first is always the one that is removed first. The fundamental operation for adding an element into a queue is called **Enqueue**, and this insertion is strictly limited to one end of the structure, which is designated as the **rear** or **tail**. Conversely, the removal of an element, known as **Dequeue**, must occur at the opposite end, called the **front** or **head**. This strict, two-ended access model—insertion at the rear and deletion at the front—is the core mechanism that enforces the FIFO order and is the defining characteristic mentioned in the question.

The incorrect option is (1):
Sort is not a data structure; it is an algorithmic process. The purpose of sorting is to rearrange the existing elements of a list or array into a specific, ordered sequence, such as ascending or descending. This process involves the comparison and potential movement of elements throughout the entire structure based on their values. Sorting is a manipulation of the existing data set, and thus, it does not define the rule for where a new, independent element is initially inserted into the structure.

The incorrect option is (2):
A Stack is another fundamental linear data structure, but it adheres to the Last-In, First-Out (LIFO) principle, analogous to a pile of trays. In a Stack, all access to the data structure is restricted to a single point. Both the insertion operation, called Push, and the deletion operation, called Pop, are performed exclusively at this single access point. This shared access point is traditionally named the **Top** of the stack. Therefore, insertion in a Stack takes place at the Top, not the rear end, making it an incorrect choice for the given statement.

The incorrect option is (3):
A Link list (Linked List) is a flexible, dynamic data structure where elements (nodes) are connected sequentially. While it is possible to implement an insertion operation at the rear (tail) of a linked list, this location is not an exclusive or mandatory rule that defines the structure itself. A standard Linked List allows for great flexibility, permitting insertions at the head, the tail, or anywhere in the middle by manipulating pointers. Since the question asks for the data structure where insertion *takes place* at the rear end as a fundamental rule, the more strictly defined Queue is the appropriate answer.