The correct answer is (a) 15.
The total number of people in the area is 100, and 40% of them are women, so there are 100 * 0.4 = 40 women. The number of men is 100 – 40 = 60. One-third of the men are coffee drinkers, so there are 60 / 3 = 20 male coffee drinkers. The total number of coffee drinkers is 20 + 40 = 60. The number of female coffee drinkers is 40 * 0.45 = 18. The number of female non-coffee drinkers is 40 – 18 = 22. Therefore, the number of female non-coffee drinkers is 15.
Option (b) is incorrect because 20 is the number of male coffee drinkers, not the number of female non-coffee drinkers. Option (c) is incorrect because 25 is the number of male non-coffee drinkers, not the number of female non-coffee drinkers. Option (d) is incorrect because it is not one of the possible answers.