Suppose a researcher examined a relationship between taking aspirin every day (yes/no) and the incidence of a heart attack (yes/no). The sample data showed that those taking aspirin had a lower chance of incidence of heart attack. A chi-square test on the data collected resulted in a p-value less than 0.0001. The data were collected in a well-designed randomized experiment. Which of the following conclusions is appropriate?

a. The probability that there is a relationship between the two variables is more than 99.99%.
b. For this population, taking aspirin reduces the risk of heart attack.
c. Heart attacks happened much more often for the non-aspirin takers than the aspirin takers.
d. All of the above conclusions are appropriate