Use the Normal to Model the Distribution of Sample Proportions

Use the Normal to model the distribution of sample proportions.
-The owner of a pet store is trying to decide whether to discontinue selling specialty
Clothes for pets. She suspects that only 4% of the customers buy specialty clothes for
Their pets and thinks that she might be able to replace the clothes with more profitable
Items. She decides to keep track of the customers who buy specialty clothes for their pets.
If in a typical day there are 275 customers, would be it unusual for her to find that 21
Customers buy these specialty clothes?

A) No, because it is close to the average number expected.
B) No, because it represents 8% of the customers who come to the store on a typical day.
C) Yes, because it is three standard deviations above the mean of the sampling distribution.
D) Yes, because it is two standard deviations below the mean of the sampling distribution.
E) No, because it is less than 4% away from the mean of the sampling distribution.