A case-control study with 500 cases and 250 controls was conducted to look at the relationship between blood clots and oral contraceptives. Researchers suspect that smoking cigarettes may confound the relationship between blood clots and birth control pills. The crude odds ratio was calculated and equals 3.25. You stratify your 2x2 tables by smoking status and find that the stratum specific odds ratio for smokers is 5.25, and the stratum specific odds ratio for non-smokers is 2.0. Based on these results, we would state the smoking is a(n) Confounder Effect modifier Neither a confounder or effect modifier Both a confounder and effect modifier