Kelly is making a bubble mixture for kids to play with at a backyard party. She adds of a cup of corn syrup to 6 cups of soap and water. She wants to make more bubble mixture and has 18 cups of the soap and water mixture to use. How much corn syrup does she need to add? A. cups of corn syrup B. cups of corn syrup C. of a cup of corn syrup D. of a cup of corn syrup