1. Clinical investigators in a particular hospital were determining whether either of 2 chemotherapies "A" and "B", increased the likelihood of developing severe vomiting. 1,400 cancer patients who received chemotherapy were divided into 4 groups:

• 200 received both chemotherapies A and B
• 500 received only chemotherapy A
• 400 received only chemotherapy B
• 300 did not receive either chemotherapy A or B

270 of the 1,400 patients developed severe vomiting. Of these 270, 30 did not receive either therapy A or B, 100 received only A and 80 received only B. Patients in all categories were similar in age, race, sex, medical history, and indications for surgery.

According to your calculations, which of the chemotherapies (or combination of chemotherapies) was most likely to be associated with vomiting?

a) Therapy A only

b) Therapy B only

c) neither Therapy A nor Therapy B

d) both Therapy A and Therapy B

e) these data do not provide this information