In a public opinion poll of a representative sample of a population, 1,800 people were asked to agree, disagree, or express neutrality toward the following statements. Statement A: The government should do more to protect air quality and water quality for American citizens. Result: 51 percent of the respondents agreed. Statement B: The government should punish companies who harm the environment with their business practices. Result: 20 percent of the respondents agreed. Which of the following most likely accounts for the different results?

a. The questions were not open-ended.

b. There were no welfare recipients in the sample.

c. The sample size was not large enough to be reliable.

d. The questions contained a difference in wording.