Why are cancer-causing factors in lifestyle or the environment difficult to identify?

Which of the following identifies the main culprit for america’s increasing weight gain?

What are the components of an effective weight-training program? a. conditioning, progression, generalization, overwork, balance, and recovery b. overload, progression, specificity, regularity, recovery, balance, and variety c. overwork, coordination, motivation, conditioning, regularity, and variety d. consistency, progression, rest, regression, balance, and specificity

Which of the following represents the results of a review of well-controlled studies of vitamin c supplementation on the resistance to, and recovery from, colds? there was a reduction in the duration of colds by 50% on the average. there was a slight effect on reducing the duration and severity of colds for people taking vitamin c supplements. there was a significant reduction in the duration of colds in people who consumed at least one gram a day. there was a significant reduction in the number of colds only in people who consumed > three grams per day.