Final answer:
The correct answer is C) octave. When tones are separated by an octave, they have a frequency ratio of 2:1 and sound very much alike.
Step-by-step explanation:
The correct answer is C) octave. When tones are separated by an octave, they have a frequency ratio of 2:1, meaning that one tone is twice the frequency of the other. This results in the two tones sounding very much alike. An octave is a common interval in music and is often used to create harmony and repetition.