A local corporation was interested in the purchasing habits of Monterey County residents. Specifically one of the things they were interested in was the proportions of residents that did a major home improvement project in the last year. The corporation used a list of all households to take a simple random sample of households. The researcher then visited each of the sampled homes and found that 21 of 100 homes had completed a major home improvement project. For this situation which of the following would be most likely to lead to a problem of non-response.

A. If the survey only looked at 100 households even though there are over 200,000 homes in Monterey County.

B. If the list of households only included homes that had been sold to a new owner in the last 10 years.

C. If the researchers actually visited 400 households but only 100 of them were willing to answer the questions on the survey.

D. If some of the subjects did not understand what the researcher meant by "home improvement" projects.