You have four electronic audio generators, A, B, C, and D, all producing tones near \(1200 \mathrm{~Hz}\) that are easily audible but not distinguishable by ear. When you increase the frequency of generator \(\mathrm{A}\) a little, the beat frequencies between A and B, A and C, and A and D all increase. When you increase the frequency of generator \(\mathrm{B}\) a little, the \(\mathrm{B}-\mathrm{C}\) beat frequency increases and the \(\mathrm{B}-\mathrm{A}\) and \(\mathrm{B}-\mathrm{D}\) beat frequencies decrease. Rank the generators by frequency, from lowest to highest.