Hi, how would I go about solving this question?

The probability that someone will prefer Coke over Pepsi is .56. A researcher asks 90 adults whether they prefer Coke or Pepsi, and uses the normal approximation to the binomial distribution to calculate probabilities regarding the Coke preferences among adults. What mean would the researcher use in the needed calculations? A. 22.18 B. 39.60 O C. 50.40 D. 90.56