Answer
Light, brightest to dimmest: C, B, A.
Work Step by Step
Situation B is dimmer than situation C because we are twice as far away. The inverse-square relation tells us the light from one candle would be 1/4 as dim, and having 2 candles doesn't compensate. Situation B has half the intensity of situation C. This is discussed on pages 164-165.
Situation A is dimmer than situation C because we are three times as far away. The inverse-square relation tells us the light from one candle would be 1/9 as dim at that distance, so having 3 candles doesn't compensate. Situation A has one-third the intensity of situation C. This is discussed on pages 164-165.
