If $n_1, n_2$ and $n_3$ are the fundamental frequencies of three segments into which a string is divided, then the original fundamental frequency $n$ of the string is given by:

• Correct answer
  A

  $\frac{1}{n}=\frac{1}{n_1}+\frac{1}{n_2}+\frac{1}{n_3}$
• B

  $\frac{1}{\sqrt{n}}=\frac{1}{\sqrt{n_1}}+\frac{1}{\sqrt{n_2}}+\frac{1}{\sqrt{n_3}}$
• C

  $\sqrt{n}=\sqrt{n_1}+\sqrt{n_2}+\sqrt{n_3}$
• D

  $n=n_1+n_2+n_3$

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