To multiply fractions you can follow the next formula:
[tex]\frac{a}{b}\cdot\frac{c}{d}=\frac{a\cdot b}{b\cdot d}[/tex]A.
[tex]\frac{1}{2}\cdot\frac{5}{5}=\frac{5}{10}=\frac{1}{5}[/tex]B.
[tex]\frac{1}{2}\cdot\frac{4}{5}=\frac{4}{10}=\frac{2}{5}[/tex]C.
[tex]\frac{1}{2}\cdot\frac{5}{4}=\frac{5}{8}[/tex]D.
[tex]\frac{1}{2}\cdot\frac{4}{5}=\frac{4}{10}=\frac{2}{5}[/tex]The expression has a value greater than 1/2 is the C.