In musical notation, an octave refers to the frequency interval from f to 2f. raising the pitch by one octave is just another way to say double the frequency. which of the following raises the pitch of a string on a guitar to one octave above?

a. decrease tension in the string by 4 times.
b. increase tension in the string by 2 times.
c. swap out the string with one with half the mass of the originald.

swap out the string with one with twice the mass of the originale.
press down the string half way (so that the effective length is half the original)