When the Yankelovich polling organization asked, “Should laws be passed to eliminate all possibilities of special interests giving huge sums of money to candidates?” 80% of the sample answered yes. When they posed the question, “Should laws be passed to prohibit interest groups from contributing to campaigns, or do groups have a right to contribute to the candidate they support?” only 40% said yes (Source: A Mathematician Reads the Newspaper, by J. A. Paulos, New York: Basic Books, 1995, p. 15). This example illustrates problems that can be caused by
a. Nonresponse
b. Bias in the way a question is worded
c. Sampling bias
d. Under coverage