15. On a beach, there are 50 people wearing sunglasses, and 35 people wearing sun hats. Among these, some people are wearing both sunglasses and sun hats. If a person is randomly selected from those wearing sun hats, the probability that this person is also wearing sunglasses is $\frac{2}{5}$. If a person is randomly selected from those wearing sunglasses, the probability that this person is also wearing a sun hat is
(A) $\frac{14}{85}$
(B) $\frac{7}{25}$
(C) $\frac{2}{5}$
(D) $\frac{4}{7}$
(E) $\frac{7}{10}$
15. B.

Notice that the number of people who wear both sunglasses and sun hats is $\frac{2}{5} \times 35=14$.

Thus, the probability that a person chosen at random from those wearing sunglasses also wears a sun hat is $\frac{14}{50}=\frac{7}{25}$.