Final answer:
To complete the sentence '1/5 of the balloons are ____' with a fraction, the fraction representing the missing color is c) Red.
Step-by-step explanation:
To find the fraction that completes the sentence, we need to determine the fraction of balloons that are the missing color. The given options for the missing color are: a) Blue, b) Green, c) Red, d) Floating. Since the sentence states that '1/5 of the balloons are ____,' we know that there are five equal parts of balloons. Therefore, each part represents 1/5 of the total balloons. To complete the sentence, we need to choose the fraction that represents the missing color, which is c) Red.