Mr. dotson wants to know if the neighbors on his street would be interested in a community watch. he surveys every fourth household on the street and concluded that 70% would be interested. a. not valid, because he should have surveyed people in the entire city. b. there is no way to determine if the conclusion is valid or invalid. c. valid, it is an unbiased systematic random sample. d. not valid, because he needs to survey every person for it to be accurate.