Use the normal distribution to approximate the following binomial distribution: A convenience store owner claims that 55% of the people buying from her store, on a certain day of the week, buy coffee during their visit. A random sample of 35 customers is made. If the store owner's claim is correct, what is the probability that fewer than 21 customers in the sample buy coffee during their visit on that certain day of the week?

a) 0.7224

b) 0.6628

c) 0.5987

d) 0.6915

e) 0.7486

f) None of the above