Question 19 of 30 Dr. Davies wants to find out if the amount of sleep students get makes a
difference in their performance on a standardized test. The best way of
accomplishing this is to do:
A. a causation study.
B. a survey
C. naturalistic observation.
D. an experiment.

B can prepare a survey

Explanation:

good lessons!!,

even though you have attached neither the chart nor the generalizations, i have located them online. the right answer is d, since they are asking you about a generalization. you can only infer from the chart that between 2008 and 2009 the number of employed workers decreased significantly (from over 115 millions to 107 millions approximately), which signals some type of economic crisis.