Answer:
A. exposure - use of artificial sweeteners
 disease - bladder cancer
In this research artificial sweeteners are used as the exposure that leads to bladder cancer disease.
B.                                 Bladder cancer          No bladder cancer
Artificial sweeteners      1293(a)                       855(b)
No artificial sweeteners  1707(c)                      2145(d)
Total                                3000                        3000
Cases -
- Risk factor (Artificial sweeteners) present (1293)
-   Risk factor (Artificial sweeteners) absent (1707)
Controls
- Risk factor (Artificial sweeteners) present (855)
- Risk factor (Artificial sweeteners) absent (2145)
Odds ratio or strength of association between exposure and disease
 OR= Cases with exposure/cases without exposure= a/c divided by b/d
So, the putting value ad/bc= 1293*2145/855*1707
= 1.9
 OR would be 1.9
C. this interprets that there is a 90% increase in the chance of bladder cancer if exposed to artificial sweeteners or people with bladder cancer have a 1.90 times higher odds of using artificial sweeteners compared to controls