Continuing with the study described in Exercise 5.34, once the researcher had randomly selected the sample of 100 Canadian psychologists, she decided to randomly assign 50 of them to receive, as part of their survey materials, a (fictional) newspaper article about the improving job market. She assigned the other 50 to receive a (fictional) newspaper article about the declining job market. The participants then responded to questions about their attitudes toward their careers. 

a. What is the independent variable in this experiment, and what are its levels? 

b. What is the dependent variable in this experiment? 

c. Write a null hypothesis and a research hypothesis for this study.