In a case control study the odds ratio for males is 3.75 and females is 1.69. The crude is 1.95.

Based on the calculations which of the following is true:

1. Sex is a confounder because the odds ratios are different from each other.
2. Sex is an effect modifier because the odds ratios are different from each other.
3. Because the odds ratios are different from each other sex is neither a confounder nor effect modifier.
4. Sex cannot be a confounder because it lies on the causal pathway between obesity and cancer.