Apolling firm is interested in surveying a representative sample of registered voters in the united states. the firm has automated its sampling so that random phone numbers within the united states are called. each time a number is called, the procedure below is followed. • if there is no response or if an answering machine is reached, another number is automatically called. • if a person answers, a survey worker verifies that the person is at least 18 years of age. • if the person is not at least 18 years of age, no response is recorded, and another number is called. • if the person is at least 18 years of age, that person is surveyed. some people claim the procedure being used does not permit the results to be extended to all registered voters. which of the following is not a legitimate concern about the procedure being used? registered voters with children under the age of 18 years may be underrepresented in the sample. a registered voters with unlisted telephone numbers may be underrepresented in the sample. b registered voters who have more than one telephone number may be overrepresented in the sample. c registered voters who live in households consisting of more than one voter may be underrepresented. d people who are not registered to vote may bias the sample results.