A 2014 headline reads “Sitting Is the New Smoking: Ways a Sedentary Lifestyle is Killing You, and explains the mounting evidence for ways in which sitting is bad for you. A more recent large 2015 study contributed to this evidence by following 69,260 men and 77,462 women and finding that for women, those who spent more leisure time sitting were significantly more likely to get cancer. 

(a) What are the explanatory and response variables for the 2015 study? 

(b) Is the 2015 study an observational study or a randomized experiment? 

(c) Can we conclude from the 2015 study that spending more leisure time sitting causes cancer in women? Why or why not? 

(d) Can we conclude from the 2015 study that spending more leisure time sitting does not cause cancer in women?