In a study of advanced colorectal cancer, 100 patients were randomly assigned to receive either a high dose of Vitamin C or placebo. The study concluded that Vitamin C was not effective in the treatment of advanced colorectal cancer because none of the patients with disease showed any improvement in the two groups. The cause and effect conclusion

a.cannot be justified because anecdotal evidence from other patients not in the study, shows that some people who take Vitamin C do recover from their disease.

b.cannot be justified because there could have been other systematic differences between the two treatment groups, such as age and gender, so that the two groups cannot be compared to each other.

c.could be justified because the sample size was fairly large (100 patients).

d.might be justified because randomization was used.

To investigate how trans fat consumption might affect fertility, researchers analyzed data available from 18,555 healthy women who participated in the Nurses' Health Study between 1991 and 1999. All were married and trying to get pregnant. It was reported that for every 2 percent increase in the amount of calories a woman got from trans fats instead of carbohydrates, her risk of infertility increased by 73 percent. Is the following statement true or false? "Even though this was an observational study, a cause and effect relationship between the consumption of trans fat and fertility has been established because the increase in risk is significantly more than 50 percent."

a.True

b.False