The board of directors at a city zoo is considering using commercial fast food restaurants in their zoo rather than the current eateries. They are concerned that major donors to the zoo will not approve of the proposed change. Of the 280 major donors to the zoo, a random sample of 27 is asked "Do you support the zoo's decision to use commercial fast food restaurants in the zoo? 20 of the donors said no, 6 said yes, and 1 had no opinion on the matter. A one proportion z-interval was constructed from these data to estimate the proportion of the major donors who support using commercial fast food restaurants in the zoo. Which of the following statements is correct for this confidence interval?
A) This confidence interval is valid because a sample size of more than 30 was used.
B) This confidence interval is valid because no conditions are required for constructing a confidence interval for proportions.
C) This confidence interval is not valid because the sample size is too large compared to the population size.
D) This confidence interval is not valid because the quantity np is too small.
E) This confidence interval is not valid because "no opinion" was allowed as a response.​