Correct Answer (Detailed Explanation is Below)
A.
Traversal
Detailed Explanation
Traversal is a fundamental data-structure operation. It involves visiting or processing elements according to the organization of the structure. Arrays can be traversed sequentially, linked lists can be traversed through their links, and trees can be traversed using different traversal orders.
Encryption and decryption are security operations rather than fundamental data-structure operations. Other common data-structure operations include insertion, deletion, searching, updating, and sorting, depending on the particular structure and application.