2/5 of the flowers are tulips, 5/8 of the tulips are yellow. Yellow tulpis are 5/8 of 2/5 of the flowers.
\(\frac{5}{8} \ of \ \frac{2}{5}=\frac{5}{8} \times \frac{2}{5}=\frac{1}{8} \times \frac{2}{1}=\frac{2}{8}=\boxed{\frac{1}{4}} \Leftarrow \hbox{answer B}\)
