The answer would 9 cm. All of the given choices are wrong since the measurement maybe too big or too small. Like for 9 millimeter, it would be too small for a clothespin. While 9km is too big for a clothespin, there is no such thing as a 9km clothespin. While 9 m is also too big. The approximate size of a clothespin is 3 inches, when we convert it to cm, it will be 7 cm. So 9 cm is a best approximate.