A uniformed U. S. Marine conducts an in-person survey at a social event to determine the proportion of Americans that say "yes" to the question: "Should the U. S. Government reduce military funding?" Of the 100 people surveyed, 99 of the respondents said "no." Identify the type of bias in this poll and state whether the sample proportion overestimates or underestimates the true proportion of Americans that believe that the U. S. Government should reduce military funding.