In a college,30% students fail in physics,25% fail in mathematics and 10% fail in both.One student is chosen at random.The probability that she fails in physics if she has failed in mathematics is

Question

$\begin{array}{1 1} (A)\;\large\frac{1}{10}\quad(B)\;\large\frac{2}{5}\quad (C)\;\large\frac{9}{20}\quad(D)\;\;\large\frac{1}{3}\end{array}$