When he removed it , he found that he was alone . With some difficulty , he managed to sit up and grabbed the waterskin from his bag , drinking his fill . Something was wrong . He did n't normally sleep this much , even given the opportunity . He usually did n't require much sleep .

Question: What is causing the anxiety of the subject ?
Answer: They are low on water .They are getting too many z 's .They are   low on drink .None of the above choices .