A box contains 5 red, 7 orange, 6 black, 8 green, and 4 blue marbles. Without looking, Martha reaches in the box for marbles. How many marbles must Martha take from the box to be sure that at least two marbles are the same color? A. 6 marbles B. 7 marbles C. 5 marbles D. 10 marbles

To ensure that at least two marbles are of the same color, Martha should consider the worst-case scenario. If she picked one marble from each color without repetition, she would have 5 different colored marbles (red, orange, black, green, and blue). Since she wants to guarantee that she has at least one pair of the same color, she needs to pick one more marble. That leads us to the answer: she must take 6 marbles. In practical situations, this kind of question illustrates the concept of the pigeonhole principle, which states that if you have more items than containers and want to ensure at least one container holds more than one item, you must exceed the number of containers by one. It's a fun way to think about probability and combinations in a simple context!