The correct answer is C. tree.
A hierarchical data structure is a data structure that is organized in a tree-like manner. The data elements are arranged in a hierarchy, with each element having one or more parent elements and zero or more child elements.
An array is a data structure that stores data in a linear fashion. The data elements are arranged in a contiguous block of memory, and each element can be accessed by its index.
A linked list is a data structure that stores data in a non-linear fashion. The data elements are arranged in a chain, with each element pointing to the next element in the chain.
Therefore, the only option that is a hierarchical data structure is C. tree.