Final answer:
Lake Van and Lake Tuz are both saltwater lakes located in Asia. They are characterized by their saline environments and location within the continent of Asia, particularly in Turkey.
Step-by-step explanation:
When considering what characteristics do Lake Van and Lake Tuz have in common, the correct answer to the student's question is a) "Both are saltwater lakes" as both are known for their high salt content. Secondly, d) "Both are located in Asia" is also accurate since both lakes are situated in the country of Turkey, which is part of the Asian continent. These lakes do not share characteristics with a glacial valley or glacial trough since those are typically associated with a blend of freshwater and seawater, unlike the high saline environment found in both Lake Van and Lake Tuz. Furthermore, these lakes are not related to the Danube and Rhine rivers that are significant to European geography, as these lakes are part of the unique geographical features of Asia.