B

Step 1: Understand the concept of octaves in music. An octave doubles the frequency of a note. For instance, if the fundamental frequency is $f$, then the octave frequency is $2f$.

Step 2: Recognize how intermediate frequencies are arranged between two notes. The frequencies of notes in a musical scale within an octave are spaced logarithmically, which leads to geometric progression.

Step 3: A geometric progression (GP) is defined as a sequence where each term after the first is found by multiplying the previous one by a fixed, non-zero number called the common ratio. In music, this means that if you have a note at frequency $f_1$, the next note in the scale can be expressed as $f_1 imes r$, where $r$ is the common ratio. This continues until reaching $2f_1$ (the octave).

Step 4: Each step on the scale represents a multiplicative increase in frequency. Therefore, the relationship between the frequencies in a musical scale corresponds to a geometric progression, not an arithmetic progression (AP) or any other form.

Conclusion: Hence, the correct answer is that the intermediate frequencies form a geometric progression.
Therefore, the correct answer is B.