Final answer:
A Hash Map is the data structure where each unique piece of data is linked to a unique index, similar to hash tables, allowing for efficient key-based data operations.
Step-by-step explanation:
The data structure where each unique piece of data is linked to a unique index, similar to hash tables, is called a Hash Map (option c). In a hash map, data is stored in key-value pairs, where each unique key is hashed to generate a unique index for storing the value in the data structure. This allows for efficient data retrieval, insertion, and deletion operations. Unlike Arrays, which are indexed collection of elements, or Linked Lists, which consist of nodes connected by pointers without indexing, hash maps provide direct access to elements through their keys. A Set, on the other hand, is a collection that contains no duplicate elements but does not associate values with unique indexes.