here is the question please provide why you chose the answer

A study conducted by the National Center for Health Statistics as part of the Center for Disease Control and Prevention (CDC) found that, as of 2015-2016, 39.6% of Americans over the age of 20 fit the medical definition of being obese (BMI of 30 or higher). A city known for its plentiful outdoor opportunities believes that number is lower among its residents. A representative sample of 80 city residents is collected and the BMI calculated for each (based on reported height and weight). The variable of interest is whether the resident fit the medical definition of obese. The study found 22 people in the sample fit the medical definition of obese. Select the appropriate method of calculating the standard deviation of the sample proportions under the null hypothesis. O 80 X (1 - 80) 0.396 O 0.396 X (1 - 0.396) 80 O 0.275 X (1 - 0.275) 80 O 22 X (1 - 22) 80