According to the Information Discussed in the in Focus Box

According to the information discussed in the In Focus box: "What You Really Want to Know About Sleep", which of the following statements is TRUE?

A) A naturally occurring compound called adenosine seems to be involved in producing sleepiness.
B) Sleep paralysis is a rare, progressive condition that can eventually lead to a permanent coma if left untreated.
C) Sleep researchers have demonstrated that it is possible to have extended, meaningful conversations with people who are chronic sleeptalkers.
D) Yawning is caused by having too little oxygen or too much carbon dioxide in the blood.