In a recent study of 500 males, half were given regular doses of a new drug, that is believed to help decrease the heart attacks, while the other half were given placebos. Among those who took the new drug, 5 suffered heart attacks. Among those who took the placebos, 9 suffered heart attacks. Test the claim that this new drug helps decrease the heart attacks at the 0.05 level of significance. Assume that these samples are randomly selected. What is the value of the critical value? Select one: O a. -1.084 b. 1.084 c. 1.960 O d. -1.960