Refer to the following graphs for Questions.



What was the approximate average yearly increase in the cost of wool from 1996 to 2000, inclusive

A． an attack on poorly constructed sleep research studies
B． a critique of recent scientific studies on REM-sleep
C． a warning against getting too little sleep
D． an analogy between human and non-human sleep processes
E． an overview of specific processes that may occur during different stages of sleep in humans