Please note that this response is aimed at improving the understanding, and you will need to express it in your own words in case you want to answer the given question for an assignment/homework submission.
Sequential access is where you can not access a piece of data unless you have accessed all the preceding data. For example, to reach a particular list node in a linked list, you have to traverse all the nodes falling in the path from head node to the node in question, starting from list head in strict ...
Solution is aimed at improving the understanding about sequential access and direct access, so it discusses things that might not look directly related to the answer to some readers. Please note that it is not a ready-to-submit answer.