If n₁, n₂, n₃, ....... are the frequencies of segments of a stretched string, the frequency n of the string is given by
a. None of these
b. 1/n = 1/n₁ + 1/n₂ + 1/n₃ + ...
c. n = √n₁ + n₂ + n₃, + ....
d. n = n₁ x n₂ x n₃ x ....