A body of mass, $m$ is attached to the lower end of a spring whose upper end is fixed. The spring has negligible mass. When the mass $m$ is slightly pulled down and released, it oscillates with a time period of $3 \mathrm{s}$. When the mass $m$ is increased by $1 \mathrm{kg}$, the time period of oscillations becomes $5 \mathrm{s}$. The value of $m$ in $\mathrm{kg}$ is

• A

  $\frac{3}{4}$
• B

  $\frac{4}{3}$
• C

  $\frac{16}{9}$
• Correct answer
  D

  $\frac{9}{16}$

Hence, the correct answer is option: 'D'.