(a)Why might the researcher have chosen to perform an observational study (by gathering information from past records) and not a randomized experiment (by assigning pregnant women to either the smoking or nonsmoking group at random)? Choose the best answer from the choices below. In a randomized experiment, it could be that some pregnant women who do not smoke would be assigned to the smoking group, meaning that they'd be forced to smoke. It would not be ethical to force people to smoke. An observational study should always be performed instead of a randomized experiment, so that the researcher can control the number of groups, the sizes of the groups, and which types of participants are in each group. For a randomized experiment to be performed, the researcher must ask women in the population to volunteer to take part. This would mean that there would not be any chance to include women who smoked during their pregnancy in the sample