Astudy was done on the mortality (live vs. die) of two major hospitals: carebetter and treatmore. data were collected over a period of time from five major illnesses and it was found that carebetter does better overall (i. e., has a smaller percentage of deaths). however, in each of the five illnesses separately, treatmore does better. which of the following is correct? a this is an example of simpson's paradox. b "illness" is a lurking variable in this example. c both (a) and (b) are correct. d this is an example of a negative association between variables. e this situation is mathematically impossible.