How could you tell if the powder was salt, sugar, flour, or baking soda?

Since all of the given items are considered safe and are commonly used for human consumption, the fastest way for you to tell whether if the powder presented is salt, sugar, flour or baking soda is to taste it. Each of the items have their own distinct taste and it is easier to determine which is which. Hope this answers your question.

The answer is probably c. xylem