Objective: How can you extend freshness in cut flowers?

Which of the following solutions is more sound in terms of naive physics reasoning?

Choices: A). Add 1/2 cup buttermilk to an almost full vase of cold water, insert your flowers, this will preserve the flowers. B). Add 1/2 cup of 7 up to an almost full vase of cold water, insert your flowers, this will preserve the flowers.
B).