Doubly Linked List
A doubly linked list is a type of data structure that consists of a sequence of nodes, where each node contains a data element and two pointers. These pointers, known as "next" and "previous," allow traversal in both directions. In this response, we will discuss the advantages and characteristics of a doubly linked list.

Traversal in Both Directions
One of the key advantages of a doubly linked list is that it allows traversal in both directions. Each node in the list contains a pointer to both the next node and the previous node. This bidirectional association enables efficient traversal and manipulation of the list in either direction. For example, if we want to traverse the list from the beginning to the end, we can start at the head node and follow the "next" pointers. Conversely, if we want to traverse the list in reverse order, we can start at the tail node and follow the "previous" pointers.

Memory Efficiency
Contrary to statement (a), a doubly linked list generally requires more memory compared to a singly linked list. This is because each node in a doubly linked list contains two pointers, one for the next node and one for the previous node. In a singly linked list, each node only requires one pointer for the next node. Therefore, the additional memory required for the doubly linked list can be a disadvantage in situations where memory usage is a concern.

Support for Deletion
Statement (c) is incorrect as a doubly linked list does support deletion of nodes. In fact, it can be easier to delete nodes in a doubly linked list compared to a singly linked list. When deleting a node, we only need to update the pointers of the adjacent nodes to remove the reference to the node being deleted. This can be done without traversing the entire list, making deletion operations more efficient.

Circular Implementation
Statement (d) is correct as a doubly linked list can indeed be implemented using a circular linked list. In a circular doubly linked list, the "next" pointer of the last node points to the first node, and the "previous" pointer of the first node points to the last node. This circular arrangement allows for seamless traversal from the last node to the first node and vice versa.

In summary, a doubly linked list allows traversal in both directions, requires more memory compared to a singly linked list, supports deletion operations efficiently, and can be implemented using a circular arrangement.