The results of a study exhibit nonresponse bias. Select the statement that best describes the bias in the study. There are not enough subjects in the sample. Many of the subjects in the study did not answer every question on the survey. The subjects in the study are not representative of the population, because some members of the population were not able to complete a survey. The subjects in the study are not representative of the population, because some members of the population could not be contacted or refused to answer the survey.