A mass M is suspended from a spring of negligible mass. The spring is pulled a little and then released so that the mass executes SHM of time period T. If the mass is increased by $m$, the time period becomes $5T/3$, then the ratio of $\frac{m}{M}$ is :
( A ) $\frac{25}{9}$
( B ) $\frac{3}{5}$
( C ) $\frac{5}{3}$
( D ) $\frac{16}{9}$