In an organ pipe closed at one end, the sum of the frequencies of first three overtones is 3930 Hz . The frequency of the fundamental mode of organ pipe is

For an organ pipe closed at one end, the harmonic frequencies are odd multiples of the fundamental frequency $f_1$. The first three overtones correspond to the third, fifth, and seventh harmonics, with frequencies $3f_1$, $5f_1$, and $7f_1$, respectively.

The sum of these overtone frequencies is given as 3930 Hz:

$3f_1 + 5f_1 + 7f_1 = 3930$

which simplifies to

$15f_1 = 3930$

Solving for $f_1$:

$f_1 = \frac{3930}{15} = 262$ Hz

The fundamental frequency is 262 Hz, corresponding to option B.