Who created The Four Horsemen of the Apocalypse?

Which answer best describes the tetrachord?

A) the building block within the scale that consisted of four pitches (TSTT) B) the ratio of four integers (12:9:8:6), deduced by Pythagoras, that determines the essence of the western musical scale C) the device that could produce the intervals of an octave, fifth, fourth, and whole step D) the lowest sounding pitch in a scale

Slip is an acid-resistant resin used to make aquatints

Indicate whether the statement is true or false