The options under the Questions tab are a mix of sort options and filter options. Newest, Votes and Active sort the questions by those attributes and display ALL questions (thus making the label to the left All Questions accurate). Featured, Frequent and Unanswered, however, are filters and only show questions with bounties, questions with lots of answers/views (unclear) and questions with no accepted answers respectively. In other words, those three show a subset of the questions, thus making the label All Questions inaccurate and confusing because it implies that these views are sorted views like the other three rather than filtered views.
It would be better if they were a) separated into sort and filter options, b) labeled to correctly reflect their respective behavior (i.e. "All" changes to "Featured/Frequent/Unanswered") or c) ?? I'm not sure the best answer, but the current design is misleading.
