The article was headlined, "Two Cups of Coffee Can Reduce the Risk of Liver Disease, Study Finds." A meta-analysis, based on combining nine previous studies involving 430,000 individuals, concluded that consumption of two cups of coffee a day reduced the chance of cirrhosis of the liver by 44 percent; even greater consumption was found to further reduce the risk of the disease.

a. The response variable in this study is:
b. not given in the quote above.
c. incidence of cirrhosis of the liver.
d. coffee consumption.
e. There is no response variable because it is a meta-analysis.