Suppose each set is represented as a linked list with elements in arbitrary…

Answer: union and intersection are the slowest.

Explanation: Let m and n be the sizes of the two sets represented as unsorted linked lists.

• Membership: search for a single element in an unsorted linked list — O(n) time.

• Cardinality: counting all elements if the size is not stored — O(n) time.

• Intersection: for each element of one list, check membership in the other list — O(m * n) time in the worst case (quadratic).

• Union: add all elements of the first list (O(m)), then for each element of the second list check membership in the result to avoid duplicates — worst-case O(m * n) time (quadratic).

Therefore, union and intersection are the slowest operations because they involve repeated membership checks across the lists, yielding quadratic time; membership and cardinality are only linear.