The correct answer is Mount saint helen is an active volcano that lies in Washington
The correction considers the correct use of the tense in "that-part". In that part future perfect continuous tense has been used. This tense means that the action will continue up until some point in the future. Since our question concerns a fact about an active volcano and we don't have an exact information how long it will continue. The correct revision is: Mount Saint Helens is an active volcano that lies in Washington.
