Whats the meaning of, "a man is rich in porportion to the number of things he can afford to let alone."

Based on the cause-and-effect relationship in this sentence, what is the meaning of the word illuminate? the colors and patterns on the stained glass windows were illuminated as thousands of candles burned during the special church service. a) to melt or change form b) to grow taller or wider c) to become extremely hot d) to light up or make clear