Use the Following Information for Questions

Use the following information for questions:
In a study of patients who had a heart attack, 3630 patients were randomly assigned to receive one of three treatments: aspirin alone, warfarin alone, or aspirin plus warfarin. The results showed that 20.0% of the aspirin group had another heart attack, stroke, or died, compared with 16.7% of the warfarin group and 15.0% of the aspirin plus warfarin group. The difference between the aspirin and warfarin groups was statistically significant, while the difference between the warfarin and aspirin plus warfarin group was not statistically significant.
-The non-statistically significant difference between the warfarin alone group (16.7%) and the aspirin plus warfarin group (15.0%) means that

A) the difference between the two rates, 16.7% and 15.0%, is not medically important.
B) the difference between the two rates, 16.7% and 15.0%, is medically important.
C) the difference between the two rates, 16.7% and 15.0%, is unlikely to have resulted from two groups whose true rates were identical.
D) the difference between the two rates, 16.7% and 15.0%, may have occurred by chance between two groups whose true rates were identical.