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 .

Based on the preceding passage, choose your answer for question What is causing the anxiety of the subject ?
Options are: A. They are low on water .. B. They are getting too many z 's .. C. They are low on drink .. D. None of the above choices ..
The answer is:
B.